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M.A., LL.D. 




SIR ARTHUR THOMSON did not live to see the com- 
pletion of this survey of contemporary science. He de- 
signed the scheme of the book and discussed the sub- 
jects and the method of presentation with many of the con- 
tributors. In this way his great talent for popular exposition 
was to be combined with the authority of the contributors 
in their own particular fields of research. As an expositor 
of biological science Sir Arthur Thomson was in his time 
unsurpassed. He was a Scotsman, and acquired in the pro- 
cess of a Scottish education all the skill in lecturing that his 
own talent and the Scottish educational tradition could give 
him. After he graduated at Edinburgh University he lec- 
tured at the Edinburgh School of Medicine on biology. He 
also rapidly became a popular lecturer to audiences in the 
neighbouring towns. Like other young Scotsmen of his 
time, he was influenced by R. L. Stevenson. He became 
interested in the literary presentation of science. Thom- 
son's remarkable combination of scientific knowledge with 
expository and literary ability became evident early in his 
career. He was appointed the Regius Professor of Natural 
History in Aberdeen University while he was still in the 
thirties. His elementary lectures at Aberdeen became 
famous, and nearly all students from all departments made 
a point of hearing some of them. Unlike T. H. Huxley and 
Milnes Marshall, he did not lecture on types of animals 
so much as on biological topics. He discoursed on topics 
such as the conquest of the land and the balance of life, 
unfolding his knowledge in the form of a story. He spoke 
with a rich Scottish accent in a low rhythm, and his 
audiences listened with rapt attention as he approached the 
climax of his drama, breaking into occasional applause as 
he turned the argument around some extraordinary pheno- 



menon of life. He could describe natural phenomena in a 
simple, flowing style, which seemed to float his audiences 
and readers over a subject. 

His long series of books included The Evolution of Sex, 
which he wrote in collaboration with the late Sir Patrick 
Geddes; the Gifford Lectures delivered at St. Andrew's 
University and given the title of The System of Animate 
Nature; the large volumes, Life: Outlines of General Bio- 
logy, also written in collaboration with Sir Patrick Geddes. 
The best known of his more popular books is The Outline 
of Science. It had an immense success, and did much to 
stimulate the admirable public taste for summaries of 
scientific knowledge. Other popular books by him are The 
Science of Life, The Biology of Birds, and The New Natural 

Sir Arthur Thomson received many honours. He gave 
the Terry Lectures in Yale University in 1924. Honorary 
degrees were conferred on him by the Universities of Edin- 
burgh, McGill, California, and Aberdeen. 

Science Today is the last effort of Sir Arthur Thomson to 
fulfil the task for which he was naturally endowed : the ex- 
position of science to the people. 

J. G. C. 


THE modern world is in turmoil. Every aspect and 
activity of life is changing rapidly. Industry, politics, 
science exhibit within their spheres the changing 
activity seen in the totality of human life. In the modern 
world science is peculiarly important, and has more influence 
on life than in any other historical period. 'The most im- 
portant of modern cultural pursuits may be expected to show 
with special emphasis the changing activity characteristic of 
the times. What has science to say concerning man himself? 
What is the state of knowledge concerning man? How is this 
knowledge changing and in what direction? What are the 
answers to similar questions concerning the methods, the 
philosophy of science? Do the fundamental concepts of 
science show a change? The status of determinism, of caus- 
ality, must be discussed. If the status of these concepts is 
changed, the concept of nature is changed. These notions are 
the Frameworks by which nature is seen, the scaffolding 
through which contact is made with the universe. Besides 
considering modern scientific knowledge of man and his in- 
tellectual mechanism, the newest information concerning his 
environment must be considered. Accepting without question 
the efficiency of the methods employed in scientific study, 
the new facts revealed by application must be reviewed. The 
methods af^science may be eternal; it is not necessary to sup- 
pose that the methods change in order that further scientific 
knowledge should be gained. A continual increase in scien- 
tific knowledge through the steady application of eternal 
methods is not inconceivable, though improbable. The new 
knowledge concerning the environment of man, the nature 
and scale of the universe which contains him, the earth which 
bears him, and the materials of which he and his environ- 
ment are made, must be reviewed. When this has been done 


the place of science may be assessed. Its relations to regions 
outside or beyond its sphere may be discussed. The student 
of such discussions can consider the state of modern scien- 
tific knowledge as an outcome of centuries of scientific work. 
He can see where science has arrived and learn the peculiar 
perspective in which it reveals the present and the future of 
man, his ideas and his environment. 

The late Sir Arthur Thomson designed this book to provide 
the serious but non-specialist reader with a series of discus- 
sions of the state and outlook of modern science in its main 
branches. Each essay has been contributed by an authority 
eminent in exposition besides learning. The contributors 
have been sought in many countries. 

A successful guidance of the changes in modern life is the 
chief need of the day. An acquaintance with the changes in 
science and the scientific accounts of the various aspects of 
life will help man to discover how this guidance should be 
made. When man is involved in material and spiritual tur- 
moil he needs strength to accomplish the achievement of 
control. He should be given confidence in his own abilities. 
This is done best by helping him to understand his own 
powers and for a, while encouraging him to consider himself. 
In periods of stability when the possibilities and duties of 
man are fairly clear he had better concentrate on the accom- 
plishment of what clearly should be done. He need not think 
of himself because his duty is obvious. When life is clear and 
stable it is relatively easy and man has confidence in his 
ability to manage it; he need not give much attention to his 
personal problems, but devote himself to the performance of 
objective duties. This happy attitude is not possible in periods 
of change. The prospects of life change; man often finds them 
too difficult and becomes afraid of them. The essays in this 
book are arranged in consonance with the view that men must 
proceed from themselves outwards in a period of change. He 
must understand his own potentialities and be inspired by 
new knowledge concerning himself. A discussion of heredity 
in human affairs is the point of departure in the journey 
through the regions of modern science. After discussing this* 


most active of the branches of the biology of human nature, 
other biological aspects of human nature are considered 
those involved in medicine and general anthropology. After 
learning of the general biological aspects of man physiology 
may be appreciated, and physiology is the appropriate pre- 
ceder of psychology. With a knowledge of heredity, medicine, 
anthropology, physiology and psychology, sociology may be 
studied, and then an essay on an important aspect of socio- 
logy theology. This completes the survey of the sciences in 
which man himself is an important object of study. After the 
study of the sciences of man follows the study of the sciences 
of his environment, and is started with chemistry, which 
describes the properties of familiar matter. This is followed 
by physics, which is concerned with the quantitative aspects 
or matter. After learning of the nature of familiar matter, the 
nature of the earth, which bears humanity, is discussed. 
Geology is the next discipline. After the earth the stars are 
considered, in order to find what place the earth occupies 
within the universe. With a knowledge of the facts of the 
sciences of man and his environment reflection is appropriate. 
The techniques of the sciences which have provided these 
facts must be scrutinized, so mathematics, logic and causality 
must be studied. An insight into fact and technique allows 
their meaning to be discussed, so the journey ends in philo- 
sophy, and the journey from the concrete to the abstract is 
completed. This order is the reverse of that often followed in 
general surveys of knowledge. There is a tendency to assume 
that the abstract sciences are more important than the con- 
crete sciences, that the more different is the subject-matter 
from the common things of life, the more profound and im- 
portant is the science. This tendency exhibits in some degree 
a contempt for humanity, a philosophical priggery. It implies 
that non-human things are more important than human 
things. This is not the attitude to be suggested by this book. 
Man should realize the extent of his knowledge of himself 
and the external world and take courage from his achieve- 
ments to face the difficulties of the day. From this he may 
proceed to the successful control of a more complicated world 


and therefore to a more interesting life. If he loses confidence 
and retreats from the complications of an interesting world 
and calls for a simplified world equal to his demeaned abilities 
he will fall into retreat. The life of society and the intellect 
will be cheapened and humanity will decline or remain sta- 
tionary for a long period. Professor Lancelot Hogben starts 
the review of Science Today with an acute statement 
of present knowledge of the biology of human heredity. 
His contribution is peculiarly timely. He is an extremely 
active research worker in this field, and what he has to say 
comes straight from the workshop of science. This is his first 
general review of a field to which he has devoted years of 
research. He is one of the three or four biologists in the world 
who are equipped to make important contributions to the 
biology of human heredity. This subject can no longer be 
usefully discussed without a considerable acquaintance with 
mathematics, and few biologists are also mathematicians. 
Besides a knowledge of biology and mathematics the effective 
worker must have a wide and active apprehension of the 
common affairs of human life. He must be able to see which 
aspects of human affairs are both important and susceptible 
of scientific treatment. Few of the facts of human and other 
nature are at present amenable to scientific discussion; the 
technique of science is as yet not developed enough to give 
useful knowledge concerning more than a few of the facts 
which are the raw material of science. Exceptional judgment 
or general intelligence is necessary in order to select these 
facts of human heredity which may through scientific discus- 
sion provide an insight into the social possibilities beyond the 
present social facts. But this is not enough. The facts of 
human nature are extremely complex and therefore cannot 
be discussed scientifically without mathematical analysis. 
Professor Hogben has recently shown mathematically that it 
should be possible to learn a great deal more about the heredi- 
tary characteristics of men than had been believed. The 
study of human heredity is complicated by the absence of 
experiment. Scientists are not allowed to control the mating 
of men and women, so they must deduce the peculiarities or 


their hereditary constitutions from an analysis of the charac- 
teristics of human families as they are found. The science of 
human heredity is consequently a science of secondary details, 
in which progress must be made by deep mathematical an- 
alysis of the related characters of cousins, twins and other 
remote or special examples. The material of the science is 
one of the least amenable to the intuitions of common sense. 
General intelligence is very necessary in the student of human 
heredity, but it will carry him much less farther in his studies 
than the experimental physicist can be carried by general in- 
telligence in the study of atomic constitution. Mathematics 
is even more important in heredity than in physics because 
human prejudice is much more likely to distort the under- 
standing of man than of things. With his wide intellectual 
equipment Professor Hogben is able to show that racialist 
theories of society have no scientific foundations. They may 
be right or they may be wrong, but as yet science cannot 
decide. He concludes that the sociological behaviour of man 
is probably influenced as much by the acquisition of habits 
as by hereditary constitution. If social organization is to be 
improved, it will be done through the learning of different 
habits rather than by breeding a new sort of man. The central 
nervous system by which a man co-ordinates his behaviour 
more probably contains the solution of the problems of 

Sir Leslie MacKenzie prefaces his review of medicine with 
interesting comments on the work of the chief historical 
figures. He shows how Hippocrates introduced or greatly 
emphasized scientific method in medicine by directing study 
to the actual patients. Careful records of the course of dis- 
eases were made, and the treatment of subsequent cases was 
based on the facts of the previous records. This process of 
observation to obtain facts upon which forecasts could be 
made was strictly scientific. Hippocrates said in an extant 
work that unsuccessful experiments besides successful experi- 
ments should be recorded, because it is necessary to know the 
causes of failure. Here he was emphasizing the necessity for 
objectivity in scientific observation. Hippocrates made some 


of the earliest contributions to scientific philosophy besides 
medicine. In his work and that of his school the contributions 
towards the construction of a scientific method are almost as 
important as his contributions to medicine. The debt of 
science to medicine is particularly clear in the Hippocratic 
writings. Six hundred years later Galen in his treatises showed 
a great extension of medical knowledge and method, to be 
expected after the experience of six centuries. His intellect 
was not as brilliant as that of Hippocrates, but he was indus- 
trious and original. He collected all the known medical 
knowledge. The mere accumulation of facts and recipes 
began to provide the possibility that medicine might become 
an experimental science. Paracelsus extended the experi- 
mental method in a revolt against Galen's authority. He 
contended that alchemy should be justified not by attempts 
to make gold and silver, but to provide the supreme sciences 
which could be directed against disease. He clearly expressed 
the modern idea that the practice of medicine should be based 
on scientific research, as partially distinct from medical re- 
search. Not all research of importance to medicine should 
be made by doctors. Medicine should be founded on the 
supreme sciences of chemistry, physics, etc., and these should 
be cultivated by their own professors. The emancipation of 
scientific research concerned with medicine from the preroga- 
tive of medical doctors resembles the emancipation of learn- 
ing from the church. In earlier periods the study of philo- 
sophy and learning was confined to the religious clerks. By 
a short explanation of the contributions of the chief medical 
geniuses in history Sir Leslie MacKenzie prepares the reader 
for an account of modern medical research and the advances 
in medical technique. The general reader will learn some- 
thing of the developments in diagnosis, in teamwork and in 
other aspects of modern medicine. 

Dr. Marett concludes in his review of Anthropology that 
rgligien. is concerned with man's orientation towards the un- 
known. Its functionjs to maintain awareness of ..thfiJiapor- 
t^s^^tEe^^nowr^as^ the squrcejof the new. A failure of 
religion causes a loss of respect for the unknown and a change 


of attention from it to the known. It implies a loss of belief 
in possibility, and hence in progress and development. 

The facts of anthropological history suggest that mankind 
has, on the whole, succeeded in the pursuit of good; which 
gives the point to life. The certainty of this fundamental con- 
clusion is reinforced by the objectivity of anthropological 
methods of investigation which, unlike those of ordinary 
history or the history of civilization, have the detachment of 
a science. Anthropology is to be classed with the biological 
sciences, and possesses their natural historical method. The 
importance of anthropology is in its breadth and objectivity, 
which give unequalled confirmation to the belief in the value 
of life, the basis of culture. 

Professor Leathes shows how the science of physiology has 
grown out of the need of medicine to understand the human 
body. Medical treatment could not be restricted to the ex- 
ternal marks of disease; it required to be directed towards 
the origin of the disorder. This could not be done without a 
knowledge of its constitution, structure and mechanism; and 
the motive led to the development of the sciences of chemistry 
and biology. Physiology is the basis of modern medical 
knowledge. Professor Leathes explains why experimentation 
on animals has been so important in research, and why the 
physiologist should be acquainted with the sciences of plant 
and animal behaviour. He gives in some detail an account of 
several important physiological mechanisms, such as the cir- 
culation of the blood. What is the effect of descriptions of 
the mechanics of the body? The reader is profoundly im- 
pressed by their subtlety. The arrangements of a living body 
for meeting its tasks in life are of a bewildering complexity 
and perfection. Adjustment is qualified by adjustment, and 
this adjustment by yet another, until an infinitude of inter- 
actions merges into the quality named living. Thus an adap- 
tive power of indescribable subtlety becomes an outstanding 
or definitive characteristic of a living body, of life. The 
student of physiology learns a standard in the science of 
organization. He sees in the human body a superb organiza- 
tion of unit cells. And yet a great deal of this organization 


operates without consciousness. Even the bodies of the lower 
animals exhibit a comparable degree of organization. If all 
this is operated below the level of consciousness, what is the 
importance of conscious organization or planning? Professor 
Leathes finds that the extraordinary degrees of organization 
below the level of consciousness revealed by physiological 
research are a ground for caution in estimating the value of 
conscious planning. Much is heard today of the necessity 
for conscious planning. Physiology shows that in the evolu- 
tion of the human body a marvellous degree of organization 
has been achieved without conscious planning, which seems 
to suggest that the proper method of evolution may be a 
method of subconscious adjustments. The proper method of 
social evolution may, by analogy, also consist of subconscious 
adjustments. As the human mind cannot as yet grasp more 
than the barest outline of the organization of the bodily 
structure, may not the human mind be rash when it tries to 
produce rational schemes of society? May not these be lack- 
ing in the infinite subtleties necessary for the perfect organi- 
zation of living beings, and which in evolutionary history 
were not consciously produced? 

Professor Lloyd Morgan discusses the delimitations of the 
science of psychology in order to discover what lies beyond 
it. He explains that the science of physics deals with a closed 
system of material entities. It sets forth the laws which 
describe the sequence of events in the material world. As the 
entities in the material world are supposed to exist whether 
they are observed or not, they may be considered to move 
within a closed system, to which an observer is not essential. 
In the same way psychology deals with the contents of a 
closed system of entities known to mind, to a closed system 
of ideas. When psychology and physics are defined in this 
manner they are conceived as descriptions of the sequence of 
events in two different types of region. Both are concerned 
with the description of what happens in their appropriate 
region, one with a sequence of ideas and the other with a 
sequence of events. Laws summarizing the respective se- 
quences are discovered and used to forecast future occur- 


rences. The psychologist will say what is to be expected as 
the outcome of a given sequence of ideas, and the physicist 
will say what is to be expected of material bodies when they 
have been in certain conditions. Both psychology and physics 
describe how something behaves and not why that some- 
thing behaves. It is clear that science, as exemplified by the 
sciences of psychology and physics, ignores the factor of 
activity, the agent which makes things behave, or the quality 
in them which accounts for their behaviour, their behaving 
quality. Activity is therefore outside and beyond science. It 
may in theology be identified with the divine principle. The 
psychologist need have no difference with the artist, historian 
or theologian who finds the explanation of his system in terms 
of the directive activity of human or divine agents. 

Mr. Christopher Dawson gives a critical examination of 
current conceptions of sociological science. He contends 
that most of the current theories of sociology fail in important 
points to possess the characteristics of a scientific theory. The 
creation of a genuinely scientific theory of sociology is prob- 
ably the most important cultural need of the day, as the 
failure to produce a scientific sociology implies that society 
and human culture cannot be comprehended by science. If 
that is so, scientific civilization is, impossible because there 
can be no theory upon whidP^actice may be founded. 
Modern civilization is not scien* 8 ^ because, in spite of the 
huge development of science, sc c ^tific method is not em- 
ployed in the organization and 'practice of politics. Mr. 
Dawson does not consider the previous failure to create a 
scientific sociology implies that such a sociology cannot be 
created. He finds the explanation in the nature of the material 
of sociological science. Like zoology, sociology is presented 
with an enormous quantity and variety of material which 
confuses the student. Some methods of handling and compre- 
hending the material are needed. Immense labours were done 
in biology before the theory of evolution became established, 
and equal or greater labours may be necessary in sociology 
before similar general laws emerge. Frederic Leplay's socio- 
logical method is probably the most promising. He studied 


at first hand the social and economic organization of families 
of different social and national types. This provided valid 
material for the construction of a genuine scientific theory of 
family life. Similar methods should be applied to the larger 
social units such as the rural community, the city and the 

The Rev. M. C. D'Arcy reviews the present state of the 
relations between science and theology. He contends that the 
recent difficulties which have arisen in the philosophy of 
physics have reduced the exaggerated claims or the scientists 
concerning their monopoly of knowledge; they have begun to 
realize again that the scientific method is only one of those 
capable of attaining truth. The tremendous successes of 
science during the last three hundred years have blinded 
many to the philosophical sacrifices by which these successes 
were purchased. Bacon and his successors flung over the 
attempt to reach a synthetic view of the world, they refused 
any longer to dance in the philosophical rings propounded by 
the ancients. They ignored the view of things as a whole 
and concentrated on the study of particulars. This anarchism 
was at first attended by immense scientific achievements, but 
has now led to unwieldy developments of isolated branches 
of science. After thre, r Buries of concentration on their 
subject physicists ha- /vfcnc themselves forced to consider 
the nature of their fi. /^o les < iples Success had caused them 
to believe that every* % ve uight be explained by these prin- 
ciples, but it is now clear that the principles of physics are 
not the basis of the world, but a limited technique for under- 
standing merely a part of it. As theology could not be re- 
duced to a part of the philosophy of science, it could not be 
accepted as a fundamental branch of knowledge by those who 
regarded science as the only basic knowledge. Theology 
could have no place in the philosophy of those who believed 
science had the exclusive route to reality. The attempts to 
base theology on science must always be sterile. Now that the 
limitations of science are beginning to be appreciated the 
development of an adequate modern theology is possible. 
Mr. D'Arcy's essay completes the review of the sciences in 


which man himself is an important subject. It is followed by 
the first of the reviews of the sciences of man's environment. 

Professor Masson's essay on chemistry introduces this 
section. He describes very simply some of the leading ideas 
of chemistry and finds the chemists' fundamental motive to 
be a desire to make a picture of the mechanism of phe- 
nomena. The chemist starts from the qualitative properties 
of materials. Qualitative differences between materials are 
particularly important in chemistry. In physics they are also 
fundamental, but the quantitative aspect has a greater part 
in physics than in chemistry. The chemist learns the precise 
qualities of the material environment of man. He is con- 
cerned with the preparation of pure specimens of the ele- 
mentary materials of this environment. When he has pre- 
cisely determined the qualities of matter he proceeds to the 
analysis of its structure. The atomic theory of the structure 
of matter was first developed by Dalton, who was a chemist. 
It has gradually passed into the hands of the physicists, as 
the theory of the structure of matter became more and more 
remote from the qualitative account of matter from which it 
started. Professor Masson finds that chemistry as such can 
have no particular implication beyond itself. He believes 
chemistry cannot determine the nature of ultimate reality. 
The chemist cannot indulge in philosophy without abrogat- 
ing the principle which governs his working life. The practice 
of chemistry shows that no man can safely trust his cogita- 
tion about nature. Scientific scepticism is the root of scientific 
method; it is not an axiom or an article of faith, but simply 
the austere wisdom born of millenia of experience. 

In his essay on the Trend of Physics, Professor Eve 
sketches the ideas which have had so profound an effect on 
modern thought. He describes, as far as they can be described 
in words, the notions of the new wave-mechanics of matter. 
He explains that the waves of the new wave-theory are not 
material waves. They are not analogous to waves in any 
medium, such as waves in the sea, or sound-waves in air. 
They are quite different in nature from the waves which 
physical theory hypostatizes for the explanation of radio 


transmission. Ether-waves are a convenient hypothesis. If 
such a thing as an ether existed, waves in it would have effects 
similar to radio waves. The new waves connected with matter 
have not even the degree of reality possessed by radio waves; 
they are waves of probability. The new wave-theory of matter 
does not state that matter is made of a sort of wave, but that 
the appearance, the being, of matter in any place is governed 
by waves of probability. The chances that matter may appear 
in any particular place can be calculated by the new me- 
chanics. Modern experimental observation has shown that 
the exact position of a particle cannot be determined, not 
because methods of observation are inexact, but because all 
methods of observation interfere with the particle, so that at 
the end of the observation its state is not the same as at the 
beginning. The recognition of this fact has shown the exist- 
ence of a hitherto unsuspected subjective element in observa- 
tion, and has caused a revision of the philosophy of physical 

The late Professor Joly describes the brilliant theory of the 
revolutions in the earth's crust to which he made such large 
contributions. He shows that the earth's crust has, as it were, 
a 'life/ It is in continual movement and passes through a 
cycle of changes, each of which occupies tens of millions of 
years. The great geological revolutions correspond to the 
periods of mountain building in the earth's history. The 
existence of these epochs of mountain building is well estab- 
lished by the presence of the newer mountain ranges such as 
the Alps and Himalayas, and by the worn stumps of ancient 
ranges exhibited, for example, in the Killarney hills. What is 
the explanation of the origin of these revolutions? Professor 
Joly found it in the radioactive substances in the material of 
the earth's crust. Their presence causes the earth to accumu- 
late heat, in spite of the escape of heat by radiation from its 
surface into space. The heat accumulates steadily through 
an epoch of tens of millions of years until it causes catas- 
trophic changes in the structure of the earth's crust. 

Professor Herbert Dingle analyzes the methods of 
astronomy in order to elucidate the proportions of fact and 


fiction in astronomical theories. The discoveries of modern 
astronomy have recast men's ideas concerning the universe 
in which they find themselves, and it is necessary to deter- 
mine with what degree of finality the new picture of the 
universe is to be accepted. Analysis shows that the facts of 
astronomical observation are to be accepted with graduations 
of certainty from high to low, but that a considerable part of 
the facts have a high degree of certainty. The theories in- 
vented to explain the observations are mental constructions 
and are more susceptible to revision and variation. A new 
observation does not affect old observations, it is merely an 
additional piece of knowledge; whereas it may prompt the 
invention of a new world-picture. The classical example of 
this is the result of the Michelson-Morley experiment. The 
single new fact was an addition of but one new fact to the 
previous body of astronomical facts, but the world-picture 
prompted by it was profoundlv different from that prompted 
bv those previc 

)y those previously known. The recognition of the large con- 
tribution of the human imagination to the construction of a 
picture of the universe made astronomers more modest in 
their pretensions. They realize that whatever grandeur be- 
longs to the universe has been created by themselves, and 
they hesitate to proclaim it. 

Professor George Birkhoff finds that the renewed interest 
in mathematics has been caused by research in physics and 
logic. The classical physicists attempted to picture to them- 
selves the course of all physical phenomena. They were not 
happy until they could see in their mind's eye the sequences 
in the changes of a material body. Mathematics was used as 
a probe for discovering the parts of this picture. The dis- 
covery of the quantum of action has shown that it is im- 
possible to imagine pictures of the most refined aspects of 
atomic behaviour. Mathematics is no longer merely a tool for 
drawing pictures which help to understand: it is the only 
mental weapon for interpreting the results of modern physical 
experiment. Its status is raised. The philosophical importance 
of mathematics was increased when Boole showed that logic 
is a sort of mathematics in which all quantities are zero or 


unity. The increase in knowledge has caused man to feel that 
he is surrounded by abstractions. The intellectual edifices of 
philosophy and science appear to him too formidable. Mathe- 
matics is his chief weapon for subduing this strange environ- 
ment, making it manageable, and allowing him to see through 
it to the fundamental permanences. 

Professor Antonio Aliotta explains why the introduction 
of a dynamic principle is the main achievement of modern 
research in logic. The old logic described the relations of 
phenomena statically, so that the rational world appeared as 
a system of unchanging essences and laws. In this system no 
place was left for change, and history consequently became 
unintelligible. Modern logic attempts to envisage rationality 
in a manner consonant with the most concrete exigencies of 
history and the human will. 

Professor Aliotta outlines his own philosophy of experi- 
mentalism. He considers that experiment should be the 
criterion of truth in philosophy as in science. But experiment 
as a test of truth is irreconcilable with the older criterion of 
truth which rested on correspondence with reality, because it 
implies an interference with reality. An experiment always 
makes something new. It is not merely a confirmation or 
denial of what was previously known or suspected, but a 
movement to a new region of deeper and more comprehen- 
sive intuitions. A dynamic theory of rationality is necessary 
to meet the dilemma of freedom and predestination which 
remains insoluble in the static mode of conceiving rationality. 

The revered Professor Max Planck discusses the concept of 
causality in the light of the quantum theory which he 
founded. The discovery that action is not a continuous phe- 
nomenon, but can happen only in finite quantities, was the 
first break with the fundamental ideas of classical physics. 
The existence of finite quantities of action fixes a limit to the 
possible accuracy in measuring phenomena. Haisenberg has 
expressed this law in his principle of uncertainty, and many 
philosophers have supposed that the impossibility of exactly 
determining the position or motion of an electron implies 
that matter possesses a certain freedom of action. If the 


future behaviour of an electron cannot exactly be calculated, 
not because of defects in apparatus, but in the nature of 
things, the law of causality no longer comprehensively applies 
to material bodies. Professor Planck minutely examines the 
implications of the limitation of the application of the law of 
causality to the behaviour of electrons, and discusses what 
relations, if any, it has to the free-will problem. He takes a 
central position between the determinists and indeterminists, 
and finds that determinism reigns in an ideal world which 
exists, but is not accessible to the human intellect. 

Professor A. E. Heath in his essay on Philosophy and Con- 
temporary in Science summarizes the effects of advance in 
physical and biological science on philosophical ideas. The 
movements noted in more detail in the previous essays are 
arranged so that the reader may receive a general impression 
of the influence of science on human ideas concerning nature 
and life. He prefers to name the synthetic summary of the 
effects of science * synoptic science ' rather than philosophy. 
He concludes that the changes in scientific ideas have been 
more disturbing to science than philosophy. The character 
of the concepts devised by scientists to explain the strange 
new facts discovered by physical research is not unfamiliar to 
philosophers. The new concepts are not as surprising as the 
long period science has succeeded in progressing without 

Science has changed the temper rather than the content of 
philosophy. It has communicated to philosophy a more 
rigorous analytical technique and has diminished the con- 
struction of speculative synthetic systems. It is qualifying as 
the tested foundation for a more satisfying social order, and 
may be to a new and brighter era what belief in providence 
has been for the old. 

J. G. C. 

March, 1934. 






By LANCELOT HOGBEN, M.A., D.Sc., Professor of 
Social Biology in the University of London. 


Medical Member of the Scottish Board of Health; Honorary 
Trustee, Kentucky Frontier Nursing Service. 


By R. R. MARETT, M.A., D.Sc., Rector of Exeter Col- 
lege; Reader in Social Anthropology, University of Oxford. 


By J. B. LEATHES, M.A., F.R.S., sometime Professor of 
Physiology in the University of Sheffield. 


By C. LLOYD MORGAN, D.Sc., F.R.S., sometime Vice- 

Chancellor of the University of Bristol. 


By CHRISTOPHER DAWSON, M.A., Lecturer in Cul- 
tural Evolution, Exeter University College. 


By the REV. M. C. D'ARCY, S.J., Campion Hall, Oxford. 





By IRVINE MASSON, D.Sc., Professor of Chemistry in 
the University of Durham. 


By A. S. EVE, D.Sc., F.R.S., Macdonald Professor of 
Physics, McGill University, Montreal. 


By the late JOHN JOLY, D.Sc., F.R.S., sometime Pro- 
fessor of Geology and Mineralogy, Trinity College, Univer- 
sity of Dublin. 


By HERBERT DINGLE, D.Sc., Assistant Professor of 
Astrophysics, Imperial College of Science, London. 


By GEORGE D. BIRKHOFF, Sc.D., Professor of Mathe- 
matics in Harvard University. 


By ANTONIO ALIOTTA, Professor of Philosophy in the 
University of Naples. 


By MAX PLANCK, Foreign Member of the Royal Society; 
President of the Kaiser Wilhelm Geselhchaft; sometime 
Professor of Theoretical Physics in the University of 
Berlin; Nobel Laureate. 


By A. E. HEATH, M.A., Professor of Philosophy in the 
University College of Swansea. 

INDEX 395 




Professor of Social Biology in the University of London 

THE scientific study of human inheritance is a very 
new department of knowledge. It need not surprise 
us that in some quarters comprehensive claims have 
been put forward on its behalf. One school of opinion holds 
out the promise that a deeper understanding of the laws of 
human inheritance can disclose a clue to the rise and fall of 
civilisation, and contends that such knowledge can provide 
the only basis for a substantial improvement in the common 
lot of mankind. The grounds for such assertions are open to 
many criticisms. The basic problem of social evolution is not 
pre-eminently the origin of new types of men and women 
in a slowly changing physiographical environment. First and 
foremost it concerns the generation of new modes of behaviour 
in a rapidly changing man-made environment. In this 
respect human society has no close parallel among social 
organisms. If the laws of its development are ever brought 
into direct relation with the behaviour of other organisms, 
the study of the central nervous system will have far more to 
contribute than the study of reproduction. The most formid- 
able problems of contemporary society do not arise from 
limitations in the ability of men and women to command 
the resources of nature. They arise from imperfect co-ordina- 
tion of human effort. Time will show whether human in- 
genuity can discover forms of organisation which will 
guarantee the continued development of a mechanical civil- 
isation. If mankind with its present endowments lacks the 
capacity to do so, the application of genetic knowledge can 
only offer a very remote prospect of producing a race of 
people which will. 

Man is the most teachable of all animals, above all an 



animal with an unusually complex development of the in- 
vestigatory reflexes, and the only animal with an elaborate 
system of communication through the medium of speech, 
which exercises a predominant influence upon his social rela- 
tions. Because of this, human society is a unique biological 
phenomenon, with unique laws of evolution. It does not follow 
that biology has nothing to teach us about social evolution. 
It does not follow that history, the descriptive study of how 
human behaviour patterns change from one generation to 
another, must always remain a science isolated from the field 
of biological enquiry. It means that a biological interpreta- 
tion of human society and of human history, in so far as it is 
possible to undertake such an interpretation, must widen its 
scope beyond the narrow boundaries enclosed by the study 
of human inheritance to include everything we can find out 
about the physiology of speech, of learning, of hand and eye 
co-ordination and a host of kindred topics which are con- 
cerned with the specific characteristics of Man as a vertebrate, 
and with the fact that human societies differ from the most 
complex communities of social insects in their pre-eminently 
dynamic character. 

At present those who study inheritance fraternise but 
seldom with nerve physiologists. In the past genetical dis- 
cussion of questions touching upon their common field of 
interest has been very largely influenced by the teachings of 
the instinct psychologists of a bygone generation. For this 
reason many speculations upon social evolution prompted by 
the influence of the natural selection theory in its earlier 
phase must now be re-examined in the light of modern work 
on the central nervous system, as well as from the genetical 
standpoint. The study of behaviour in the lower animals 
reveals the existence of many simple reflex patterns which 
are consistent with a very wide range of external conditions. 
What has emerged pre-eminently from modern work such 
as that of Pavlov's school is that the relevant environment in 
which the behaviour patterns of the higher animals arise is 
not a fixed and static, but a dynamic and ever-changing 
pattern of stimuli; that this ever-changing pattern of stimuli 


generates new patterns of conditioned reflexes and that the 
chronological no less than the spatial relations of the stimuli 
themselves are significant in producing such new patterns. 
This leaves the way open to the recognition that human 
society is a phenonemon sui generis, a phenomenon which 
owes its uniquely dynamic character to human inventiveness 
and the capacity of the human species to capitalize the fruits 
of its tool-bearing pursuits for the use of future generations 
through the medium of speech and its substitutes. Whatever 
differences of inborn constitution distinguish individuals and 
groups of individuals living in different places at different 
periods, the outstanding biological peculiarity of Man is the 
fact that an infinitude of different behaviour patterns is con- 
sistent with the same genetic basis. The instinct psychology 
of the selectionist school encouraged the belief that the 
student of human genetics would be able to detect simple 
unit characters in the domain of social behaviour. What we 
now know about the physiology of the nervous system does 
not encourage such a hope. 

Extravagant assurances put forward by writers of the 
racialist school do not alter the fact that human genetics has 
a genuine claim to be encouraged as a branch of medicine. 
Research upon cancer has very little contribution to make to 
a scientific treatment of human history or to the removal of 
war, unemployment, and other evils which threaten the 
stability of existing civilisation. None the less, it is a field of 
investigation which rightly engages public esteem. Whatever 
else it may accomplish, genetic science can teach us much 
about the factors which determine susceptibility to disease 
for which curative measures are not yet available. It may 
thus be applied to the prevention of diseases for which there 
is no simple remedy. Of itself it is not a panacea for human 
ailments. It is an essential ingredient of the kind of know- 
ledge upon which scientific prognosis must rest. Knowledge 
of this kind is not easy to gain. Special methods are necessary 
because of the intrinsic difficulty of dealing with a species 
which breeds slowly, has few offspring, and cannot be mated 
by the investigator at will. During the past two or three 


decades great progress has been made in devising such 
methods. The results achieved have a real, if modest, claim 
to be considered as contributions to preventive medicine. It 
is in the field of preventive medicine rather than in relation 
to any of the great social issues of our time that the applica- 
tion of knowledge of human inheritance lies. 

Physicians and their patients often ask the biologist 
whether tuberculous people should marry and have children, 
or whether mental diseases are inherited. Questions of this 
kind need to be stated in precise terms before it is possible 
to find a precise answer to them. The difficulty of making 
them sufficiently precise is partly due to the fact that the 
terms in which the problem of nature and nurture is dis- 
cussed are very largely drawn from everyday speech. An 
anecdote in a recent biography of Mendel illustrates this well. 
In the year 1910 a memorial was being erected to honour 
Mendel in the place where he had spent his life teaching and 
had carried out his experimental researches. Among the 
citizens there was much talk of the distinction which 
Mendel's discoveries reflected upon the town. Two visitors 
were gazing at a portrait of the Abbe displayed in a shop 
window. One asked, " Do you know who this fellow Mendel 
was ?" " Why, yes," was the reply; " he gave Briinn a bequeath- 
ing (Vererbung)" It has taken people a long while to outgrow 
this confusion between legal inheritance and biological in- 
heritance. When Darwin wrote the Origin of Species the 
phenomena of fertilisation had not been directly observed in 
any animal. Biologists still believed that people hand on their 
noses to their offspring in much the same way as they hand 
on their bank balances. Even now there are a few biologists 
of an older generation who find the prospect of a hundred- 
per-cent. death duty equally repugnant, whether it is applied 
to their bank balances or to their noses. Weismann per- 
formed a great service to biology by pointing out that the 
state of death claims all our accumulated anatomical earn- 
ings. Our parents do not endow us with what Darwinian 
biologists called "characters." They endow us with genes. 
The genes cannot carry their cheque-books into the next life. 


The modern term gene corresponds to what Mendel called 
" factors." The gene is the atom o hereditary transmission. 
It has the same logical status in genetics as the atom of 
chemistry. Like the atom, it cannot be seen. We infer its 
existence from two laws of experimental breeding analogous 
to two generalisations which led to the atomic theory of 
matter. One may be called the law of the conservation of 
hereditary matter. That is to say, it is always possible with 
sufficient trouble after a certain number of generations to 
recover individuals with the same hereditary equipment as 
the original parents of a cross between two varieties of animals 
or plants. The other might be called the law of the constancy 
of genetic proportions. In crosses between two races the pro- 
portions of the various types which appear in ensuing genera- 
tions are numerically predictable. 

In one respect the geneticist is more fortunate than the 
chemist. The larger units of physical chemistry formed by 
the combination of atoms are not individually recognisable. 
We have to infer the existence of molecules, like that of 
atoms, by indirect methods. Genes are built up into larger 
units called chromosomes, which we can actually see with the 
help of a powerful microscope. The number of chromosomes 
is the same in every one of the microscopic bricks, or cells, of 
our bodies. In Man the number is forty-eight. In both sexes 
we can distinguish twenty-three pairs, the two members of 
which are of the same size and shape. In the female the two 
members of the additional pair are of the same size and 
shape. In the male this pair is unequally mated. One member 
called the X (or sex) chromosome is of the .same shape and 
size as the twqjeiM^kinents XX QJLthe 

The other, called the Y^huromo^ome^is much 

Man, like every other animal, begins his life as a single cell 
which divides repeatedly. This single cell, the fertilised egg, 
is formed by the union of the egg contributed by the mother, 
a. cell just large enough to be seen by the eye, and a single 
microscopic cell of the seminal fluid. These cells or sperms 
are so minute that a large drop of seminal fluid contains 


enough to produce all the human beings in the United States, 
if each sperm fertilised a different egg. The fertilised egg 
contains a double set of chromosomes, one member of each 
pair of the same size and shape being contributed by the egg, 
the other by the sperm. In the repeated cell divisions which 
occur throughout development each cell gets a representative 
of each chromosome in the fertilised egg, because the chromo- 
somes themselves divide equally. An unusual type of division 
occurs in the formation of sperms and eggs. Each gamete 
(sperm or egg) gets only one representative of each pair of 
chromosomes, either a descendant of the one contributed by 
the father or a descendant of the one contributed by the 

This peculiarity of chromosome behaviour provides a clue 
to the laws which the Abbe Mendel discovered at the time 
when Darwin was writing the Origin of Species. The material 
basis of these laws was not discovered till forty years later. 
Today the behaviour of the chromosomes gives us a faith- 
ful picture of the way in which characters distinguishing 
different varieties stick together in hybrid experiments and 
also the way in which they are distributed among the sexes. 
f with an^C_chromosome 


fertilises_an egg. This explains why^Tn^^rossing Tome 
varieties the male offspring do not share the characteristics 
of the father when the female offspring do so. Differences 
between varieties of this type are due to the genes of the 
X chromosomes. 

The sperm and the egg are the only link between two 
generations common to all animals. We might define a 
difference due to heredity, or, as it is better to say, a genetic 
difference, between two individuals as a difference which has 
its basis in a different structure or material composition of 
the gametes at the time of fertilisation. A difference due to 
environment would then be a difference due to any dissimi- 
larities in the infinite number of agencies with which the 
fertilised egg reacts in the course of its development or in the 
subsequent life history of the fully developed human being. 


Environment as it is thus interpreted by the biologist includes 
the influence of maternal circulation and health on the off- 
spring between fertilisation and birth. A distinction framed 
in this way has useful theoretical implications. It does not 
help us to distinguish between differences due to environment 
and differences due to heredity, when we actually see them 
as end products in the development of two human beings. 
Before we can ask the right sort of questions about the in- 
heritance of diseases, or, to be more exact, the inheritance of 
gene differences which affect the liability to contract a disease, 
we must pause to clarify the distinction by examples which 
occur in the practice of breeding. 

If chickens are fed on yellow corn or given green food, we 
can distinguish between some varieties which breed true for 
yellow shanks and others which breed true for colourless 
shanks. This is a genetic difference. When all the progeny 
are fed on yellow corn or given green food, crosses between 
such varieties yield numerical ratios of the two types in con- 
formity with Mendel's principle. If chicks of the variety with 
yellow shanks are fed exclusively on white corn they grow up 
with colourless shanks. The difference between a fowl of the 
yellow variety brought up on yellow corn and a fowl of the 
same variety brought up on white corn is a difference due to 
environment. If we were to cross fowls of the yellow variety 
with fowls of other varieties, giving some of the progeny 
yellow corn and others white corn, we should not expect to 
obtain constant numerical ratios such as Mendel's principle 
predicts. Let us suppose that two poultry farms, both using 
yellow corn for food, specialised respectively on birds with 
black plumage and yellow shanks and birds with barred 
plumage and white shanks. We should call both differences 
genetic differences. If both farms decided to use white corn, 
we should only be able to recognise the plumage difference as 
a genetic difference. If both farms varied their procedure 
from week to week, we should not be able to tell whether the 
difference between one bird with yellow shanks and another 
bird with colourless shanks was a genetic difference or a 
difference due to environment. 


Another example may help to make the distinction more 
clear. Some rabbits deposit yellow fat when fed on green- 
stuffs. Most rabbits have white fat, whether given greens with 
their food or not. Yellow fat is a serious carcase defect from 
a business point of view, because purchasers object to it. 
Rabbits which have white fat when fed on green food possess 
a liver ferment which breaks down the yellow pigment in 
plants, thus preventing it from reaching the fat deposits. 
Rabbits which deposit yellow fat lack this enzyme. It has 
been shown that when rabbits of both kinds are crossed and 
backward crossed, the absence of the ferment behaves like an 
ordinary " recessive character " (vide infra). It is only recog- 
nisable as such if the rabbits are given green food containing 
the yellow pigment. In a group of rabbits of both types we 
can recognise the gene difference by giving them all green 
food. If we do so the biological environment is neutral in 
Professor Levy's sense, 1 and the gene difference is what he 
calls isolate, which we are investigating. If we have a group 
of rabbits none of which possesses the enzyme which breaks 
down the yellow pigment, we can make their fat white by 
feeding them on mash and potatoes, or yellow by feeding 
them on mash and cabbage. In that situation the genetic 
constitution is neutral, and the biological environment is the 
isolate of the investigation. The practical breeder has two 
remedies from which he can choose. He may either put the 
blame upon the biological environment and cut off the supply 
of green food, or he may put the blame upon heredity and 
breed for white fat. 

Sometimes the doctor can put the blame on heredity and 
at others upon environment for the manifestation of one and 
the same clinical phenomenon. A biological parallel to a 
small class included under the general term " idiots " illus- 
trates this very clearly. Cretinism is due to insufficient 
quantity of the iodine compound manufactured by the 
thyroid gland. Insufficiency of the same hormone in frogs, 
toads and salamanders prevents the aquatic tadpole from 

1 H. Levy, The Universe of Science. 


transforming into the terrestrial adult. This may be because 
the thyroid gland is incapable of doing its proper work. Even 
when it can do so, it is unable to make thyroxine without 
iodine. So if tadpoles are kept in water with no trace of iodine 
and fed upon a diet free of iodine compounds, they fail to 
transform into frogs. European newts normally complete 
their development and breed in the adult form. In certain 
mountainous districts where endemic cretinism is reported 
among human beings, the newts commonly fail to undergo 
metamorphosis, or do so after a long delay. This is probably 
because the iodine content of the waters in which they live is 
low. A similar explanation does not apply to a local race of 
the American newt (Ambystoma tigrinum) which lives in 
lakes in the neighbourhood of Mexico City. Individuals be- 
longing to this race never grow up; they breed from genera- 
tion to generation in the aquatic form. They will grow into 
the terrestrial newt if fed on thyroid gland. They will not do 
so if given iodine compounds. They possess a thyroid gland 
which does not release its secretion into the circulation. The 
Mexican variety breeds true for its inability to undergo meta- 
morphosis when kept in aquaria with access to an abundance 
of iodine compounds. 

If we compare human birth with the emergence of the 
aquatic larva upon dry land, insufficient thyroid secretion in 
the maternal circulation corresponds to keeping tadpoles in a 
tank with iodine-free water and food containing no iodine 
compounds. In many discussions of mental inheritance the 
term environment is inaccurately equated to training, and even 
to training at so late a stage as when school education begins. 
This is very misleading. The fact that a condition is con- 
genital provides no presumptive evidence for the view that 
environment is of little setiological significance. It is equally 
compatible with the belief that genetic differences account 
for its occurrence, that it is determined by idiosyncrasies of 
the uterine environment, or that both these agencies play 
their part in its manifestation. Several classes of facts point 
to the importance of exploring the influence of the uterine 
environment upon the characteristics of individuals. One is 



the high incidence of certain conditions among first-born 
children. Another is the high incidence of various malforma- 
tions among offspring of women approaching the end of the 
child-bearing period. 

When a contrast was drawn between variations in plumage 
colour and the colour of the shanks, we did not separate a 
class of phenomena to which the Mendelian principle applies 
from a class of phenomena to which it does not apply. The 
object was to distinguish between a class of phenomena which 
are easy to study and a class of phenomena which demand 
more care in controlling the environment. There is no hard- 
and-fast line between the two. Genetic differences which dis- 
tinguish plumage colour in fowls are recognisable over a very 
wide range of environment. This does not mean that they 
are just as big in every environment which human ingenuity 
can devise. The difference between the black plumage of an 
Ancona and the mottled plumage of the Light Sussex is a 
genetic difference. By adding thyroid extracts to the food 
the extent of the black areas in the Light Sussex can be very 
considerably extended. 

No statement about a genetic difference has any scientific 
meaning unless it includes or implies a specification of the 
environment in which it manifests itself in a particular 
manner. Characteristics of organisms are the result of inter- 
action between a certain genetic equipment inherent in the 
fertilised egg and a certain configuration of extrinsic agencies 
which in the case of human beings include the conditions of 
life in the uterus as well as the external environment in which 
social existence is carried on. Differences between individuals 
may arise from differences in the kind of genes present in 
the fertilised egg and from differences in the uterine or post- 
natal environment. Differences due to a difference of genes 
may be of two types : (i) differences which are recognisable in 
almost any environment in which the fertilised egg will de- 
velop and continue to grow; and (2) differences which are 
only manifest within a restricted range of environment. Ex- 
amples of the first are the difference between a " haemQ- 
philiac " and an adult whose blood coagulates in the normal 


way, or between an amauroticjamily idiot and healthy infant. 
An example of the second, type is furnished by the type of 
mental defective known as the "mongol." Whatever gene 
differences are involved in this condition appear to require a 
special pre-natal environment to make them recognisable. 

The distinction between these two classes is of the utmost 
importance from a preventive point of view. When we have 
to deal with the first we can readily determine the type of 
transmission involved. On the basis of Professor J. B. S. 
Haldane's analysis of genetic selection, in a series of brilliant 
memoirs dealing with the mathematical developments of 
modern genetics, we can predict with some confidence the 
rate at which affected individuals can be eliminated by any 
type of interference with parenthood. When we encounter 
the second it is more difficult to determine the method of 
transmission. Unless affected individuals are extremely rare, 
it is generally impossible to do so, until we can specify with 
some precision the sort of environment in which they are 
recognisable. Thus we cannot give a certain answer to the 
question, what would be the result of selective interference 
with parenthood? Usually we could deal with the matter 
without recourse to selection, if we had the kind of know- 
ledge which enables us to say how much reduction selection 
would bring about. For instance, we know sufficient today 
about the way in which people get cholera to study the genes 
involved in susceptibility to the disease among a group of 
individuals equally exposed to the danger of contracting it. 
The fact that we have the knowledge to study the problem is 
the reason why it is of no practical importance to do so. To 
understand the environmental situation is to be able to 
control it. 

We may express this important truth in another way. 
When we understand the modus operandi of the gene, we 
can state the kind of knowledge we need in order to control 
the conditions in which its presence will be recognised. As 
J. G. Crowther has remarked, pioneers of the evolutionary 
theory, being preoccupied with the shapes of animals, handed 
on the same obsession to the earlier geneticists. Out of it grew 


the belief that artificial selection is the only remedy when 
once we have put the blame upon heredity. Though we still 
believe that selection has its uses, biologists are becoming 
more critical towards the ultra-calvinistic attitude of Galton 
and his disciples. This is because the geneticist has begun to 
deal with the gene as a reagent in the process of development. 
The study of gene differences is becoming part of the dyna- 
mics of the organism. If we are content to endow a gene 
with the property of making urine black, the outlook for the 
individual patient is also black. Selection is, then, the only 
remedy for the condition known as " alcaptonuiia." If we 
envisage the gene displaced as the precursor of an enzyme 
which completes the breakdown of the meat in our food, we 
discern alternative possibilities. Biochemical discovery may 
one day make the missing ingredient available for individual 
use. Recent work on oestrin therapy for haemophilia shows 
that such a possibility is not an idle dream. The blood of 
haemophiliacs fails to clot, so that they die very often of 
haemorrhage. Only males suffer from the disease. The gene 
responsible cannot manifest its effect in the biochemical en- 
vironment of a female body. Males may be cured by giving 
them the female ,sex hormone. 

A variety of the domestic fowl known as the Frizzle helps 
us to adopt a new perspective. It has defective plumage. 
Frizzle crossbreds are distinguished by curling of the feathers 
upwards and outwards. The pure-bred Frizzle remains 
practically bare throughout its first year of life. It appears to 
be in a state of perpetual r^oulting. It is extremely delicate 
and difficult to rear. When newly hatched, the down feather- 
ing is fragile and easily breaks off. The exposure of the skin 
so produced leads to a great loss of bodily heat from the sur- 
face. This calls forth increased basal metabolism, increased 
heat production, increased heart-rate, lack of fat deposits, and 
diminished haemoglobin content of the blood. It has now 
been shown that the pure Frizzle chick will develop within 
three weeks a complete phy32 over the whole body if pro- 
tected from heat loss by enclosure in a woollen jacket and 
confined to a warm room. Knowledge of the way in which a 


single gene difference produces its deleterious manifestations 
thus teaches us how to prevent their appearance. 

Having cleared the ground of erroneous and antiquated 
notions about heredity and environment, we are now in a 
position to see what sort of questions we can intelligibly ask 
about the role of heredity in disease. One is whether liability 
to suffer from any particular disease is associated with gene 
differences. Another is whether such gene differences are of 
the kind which would be apparent throughout a range of 
environment as great as that to which members of the same 
fraternity, stock, or social group are exposed. We now possess 
methods which enable us to detect gene differences which are 
recognisable throughout a wide range of human environment 
and differences which are not. Naturally, we know most 
about the first kind, since they are simpler to deal with. All 
the best examples are derived from the study of what medical 
authorities call " hereditary " and " familial " diseases of the 

When we are studying inheritance in human beings it is 
not possible to start with pure-bred stocks. Hence if a human 
trait is recessive that is to say, if it is only manifest when 
the individual receives a particular gene from both parents 
a certain proportion of individuals who do not manifest the 
same trait receive the gene from one but not from the other 
parent. If a trait is dominant that is to say, if it is recog- 
nisable when the individual who shows it receives a particular 
gene from one parent only it may not be possible to tell 
from the appearance of any given individual whether he or 
she has received it from one or both parents. To establish 
quantitative laws of human inheritance it is necessary to 
know what proportions of people receive a given gene from 
one and what proportion from both parents. Marriage is a 
* lottery. The natural history of lotteries, or, as we more usually 
call it, the theory of algebraic probability, enables us to tell 
what proportion of individuals will derive a given gene from 
both parents or from one parent only, if we know the propor- 


tion who do not possess it. Thus the net expectation for 
different kinds of offspring of parents of a specified type can 
easily be calculated if mating occurs at random. Mating does 
not always occur strictly at random in human communities. 
A talented contemporary authoress has reminded us that 
gentlemen prefer blondes. Allowance can be made for this 
by studying the correlation between husbands and wives. 

When the possession of a physical trait does not appreci- 
ably affect the choice of a mate, it is easily shown that the 
number of individuals who carry a rare. gene on one chromo- 
some, buLBQt on its fetlow js twice the square root of the 
number who carry it on both members of SuTsame pair of 
diomosomes. The meaning of this statement may be illus- 
trated by albinism. Albinism is a recessive condition. In this 
country the proportion of albinos in the community is about 
one in twenty thousand. According to the principle of 
random mating, one in every seventy individuals who are 
not albinos should therefore carry the gene for albinism on 
one of their chromosomes. Individuals who display a very 
rare dominant condition will nearly always possess the gene 
which determines it on one chromosome only. Half the off- 
spring of such individuals, if married to a normal person, 
should have the dominant trait. This is easy to test in the 
numerous pedigrees of what medical men refer to as " heredi- 
tary " diseases or disfigurements. Such are brachydactyly, a 
congenital absence of one of the joints of the fingers, one form 
of night blindness, a somewhat repulsive abnormality known 
as lobster claw which is a deformity of the lower limb, the 
disease known as diabetes insipidus, distinguished by exces- 
sive passing of urine, Huntingdon's chorea, a disease with 
some resemblance to St. Vitus's dance, and a defect of the 
pupil called aniridia. These conform in a satisfactory way to 
the numerical requirements of Mendel's law. Except in so 
far as the supply is replenished by fresh sports (or "muta- 
tions"), they could be eliminated in a generation if indi- 
viduals suffering from them were not allowed to reproduce. 
When diseases of this class are incurable, this is the only 
effective method of prevention known at present. 


At first it seemed more difficult to identify recessive genes 
in human beings. An individual who exhibits a recessive con- 
dition must receive the gene from both parents, and may thus 
be the offspring of one of three types of marriage : a marriage 
between two recessives; a marriage between a recessive and 
an apparently normal individual who carries the gene; or a 
marriage between two carriers neither of whom exhibit the 
trait. What has been said about albinism shows that marriages 
of the last type will be much more common than the other 
two, since carriers are so much more common than albinos. 
So recessives are generally offspring of parents who are not 
themselves recessives and have no near ancestors who are re- 
cessives. They are not detected by collecting long pedigrees. 
The principles of animal and plant breeding tell us that if 
two parents are carriers one-quarter of their offspring will be 
recessives. Thus recessive conditions tend to turn up among 
several brothers and sisters in a family. In the language of 
the medical profession, they are " familial." The proportion 
predicted by genetic theory is easily tested by collecting 
sufficient cases. 

A second criterion is still more valuable, especially if the 
recognition of a recessive gene substitution depends on con- 
ditions which are not always present in the family environ- 
ment. Consanguineous parentage will always be noticeably 
more common among parents of rare recessives than among 
the general population. The proportion of consanguineous 
parentage can be stated precisely as a function of the rarity of 
the recessive condition. About 15 per cent, of the parents of 
children who die of the wasting disease called amaurotic 
family idiocy and about 10 per cent, of deaf mutes are first 
cousins. The percentage of all marriages between first cousins 
in the population at large generally varies between ^ and i 
per cent, in European communities. Without introducing 
mathematical symbols, the reason for this is easy to grasp, 
though unaided common sense is not sufficient to tell us how 
rare a recessive condition must be if we are to detect a large 
enough excess of consanguineous parentage. If I carry the 
gene for albinism on one of my chromosomes, the chance 


that I shall marry an unrelated individual who is likewise a 
carrier is only one in seventy. If I marry my cousin, I am 
marrying an individual who has received a certain proportion 
of her chromosomes from the same pair of grandparents as 
myself. The chance that the offspring of two grandparents 
will both receive a particular chromosome from one of them 
is one in eight. So, if I am myself a carrier, the odds that I 
should marry another carrier would be nearly ten times 
greater than if I married someone who was not related to me. 
About a dozen of these recessive conditions are now well 
established. One is a type of partial blindness known as reti- 
nitis pigmentosa. Amaurotic family idiocy and juvenile 
amaurotic idiocy are two other examples. These diseases, 
which involve progressive blindness, dementia, and wasting, 
are fatal, one at about two, the other at about sixteen years. 
If two parents produce an amaurotic child, the odds are that 
one-jialJ^Qf jj^ir offsjgringjwill carry the_gene ? jand one-cjuarter 
will exhibit it. It is difficult to justify the English law which 
3oes not permit such parents to avail themselves of a very 
simple operation to prevent the further spread of the un- 
welcome genes which are responsible for these two formidable 
and at present quite incurable diseases. Sterilisation of the 
individuals directly affected is in this case undertaken by 
nature, since individuals die before they can propagate their 
kind. It is an important fact that selection eliminates reces- 
sive conditions very slowly. If all albinos were sterilised in 
every generation it would take many centuries to reduce the 
incidence of albinism to half its present dimensions. Research 
upon the characteristics of individuals of consanguineous 
parentage is likely to increase our knowledge of recessive 
genes in the human species considerably. At present a larger 
number of dominant than of recessive sports or " mutants " 
are known to exist among human beings. This is contrary to 
what occurs in most wild animals. In nature dominant muta- 
tions seem to be rare. Probably there are more recessive than 
dominant mutations in Man. The apparent rarity of reces- 
sive mutations may be due to the fact that the method of 
detecting them has only been recently perfected. This is 


supported by the existence of one special class of recessive 
genes not included in what has been said hitherto. Recessive 
genes which make up the X c h ron ^omes are easily recog- 
msejcTby the factjKa^ much rarertEan 

maks. Red-green coIouFBiindness is a case oi: this 

type of inheritance. Colour-blind mates are at least ten times 
as common as colour-blind females. 

( Recessive genes known tqjbe in the X chi^om(^HilJ^ e 
more^numerous than alFtE? recessive genesTat present known 
to be located on the remaining twenty-three pairs of human 

_ . !..,!, ........ - -- ' * ------ ^" ' " -- - ~ -- J -- - '"*-J~< *.-., ..,.. -- , - - -- . _ 

cMomosomes^ No doubt this is because the peculiar type of 
inheritance fo which they give rise attracted medical interest 
more than a century ago in connection with the study of 
haemophilia. There is a strain of haemophilia in the Royal 
Houses of Europe. This leads us to ask whether a sterilisation 
policy would raise the standard of physical fitness among 
Royalty. It has been said that the sterilisation of individuals 
who display recessive conditions of the ordinary type pro- 
duces very little effect because the genes are principally trans- 
mitted by individuals who do not exhibit the recessive con- 
dition. This does not apply to conditions due to X-borne re- 
cessive genes. Since the male has only one sex chromosome, 
all males who carry the recessive gene exhibit the recessive 
trait, unless special conditions of environment are essential to 
its manifestation. Sterilisation of all individuals displaying 
"sex-linked" recessive diseases halves the proportion of 
persons affected in every generation. 

The tendency of traits to stick together has made it pos- 
sible to construct maps of the chromosomes in animals and 
plants. All the known genes of the fruit fly and the sweet pea 
can be assigned to their respective chromosomes and to a 
particular position relativfr to other genes on the same chro- 
mosomes as themselves. The genes whose manifest effects are 
easy to distinguish in human beings are mostly rare. It is 
therefore exceedingly unlikely that we should encounter two 
in the same pedigree. For this reason the possibility of con- 
structing a chromosome map of the human species seemed 
quite fantastic ten years ago. Today the prospects are very 


hopeful. The possibility of doing so has emerged from the 
study of the blood groups. 

People can be classified in four groups according to whether 
the blood of one individual when mixed with another curdles. 
The four blood groups depend upon three genes, one group 
"being recessive, one group depending on the presence of one 
dominant gene, a third on the presence of another dominant 
gene, and the fourth on the presence of both dominant genes. 
The two dominant genes have arisen by mutation from one 
and the same recessive gene. They cannot both be present on 
one and the same chromosome^ Population studies on hun- 
dreds of thousands of individuals have shown that the differ- 
ent proportions of these groups in different communities 
correspond to the requirements of the theory of random 
mating with extraordinary fidelity. Parents and offspring of 
more than five thousand families have been systematically 
examined. The results are in close agreement with what 
would be predicted, if the explanation already given is the 
correct one. Their importance for the study of human in- 
heritance resides in the fact that the frequency with which 
the three blood-group genes occur in the general population 
is much the same. Hence it is easy to test whether they tend 
to stick together with other genes. 

If blood-group testing were carried out in all records of 
hospital pedigrees, it would be possible to ascertain whether 
rare genes responsible for diseases like amaurotic idiocy or 
night blindness reside on the same chromosomes as the three 
genes of the blood groups. Blood-curdling can also be pro- 
duced by injecting sera of other animals into the circulation. 
People have now been classified for their reactions to various 
" foreign " sera. Other blood groupings of similar proportions 
have been based on such reactions, and the transmission of 
at least one such series has been worked out. It has been 
shown that the genes involved are not located on the same 
pair of chromosomes as the three genes of the Jansky blood 
groups. It is not unlikely that we shall soon be able to test for 
a blood grouping referable to every one of the twenty-four 
pairs of human chromosomes. Recently it has been shown 


that about a quarter of the population are incapable of tasting 
a group of substances allied to and including the organic 
compound called phenyl-thiourea. This substance is described 
as exceedingly bitter by those who can taste it. Ability to 
taste is determined by a single dominant gene. About as 
many people have the dominant gene as lack it. Like the 
blood-group test, " taste blindness " may play a part in the 
mapping of the human chromosomes. 

About thirty known incurable diseases are determined by 
genes whose existence is established by agreement with the 
numerical requirements of Mendel's laws. This list includes 
several forms of blindness. It does not include a long list of 
presumptive cases which will probably be added in the near 
future. We do not yet know of any enviable characteristics of 
human beings determined by single genes. Even the inheri- 
tance of the platinum blonde is still a topic for future re- 
search. The next few years will probably witness very rapid 
progress in establishing precise laws of hereditary transmis- 
sion for physical traits which are little affected by the differ- 
ences of environment to which different human beings be- 
longing to the same pedigree are ordinarily exposed. 

So far our examples of well-established genetic differ- 
ences between human beings have been taken from the field 
of medicine. There are other physical differences determined 
by genes, such as those which distinguish people of one geo- 
graphical variety or race from those of another. Differences 
of hair colour, eye colour, nose breadth, the curliness of the 
hair, stature, and the like, are true genetic differences, though 
we do not know very much about the genes which affect 
them. In most cases such differences appear to involve many 
genes, and further analysis of the way in which they are in- 
herited defies the methods at present available. Thus the 
difference of skin colour between a negro and European must 
involve at least four and probably more gene differences. 
Such differences are much less interesting to the student of 


human affairs than are differences of temperament and cul- 
ture. Many writers on heredity and human affairs succumb 
to the temptation of assuming that such differences like 
physical idiosyncrasies used to classify mankind in races are 
mainly due to different combinations of genes. When they 
do so they are not speaking as biologists. Biology can as yet 
tell us little about how such differences arise. 

At the same time it is natural and proper to ask whether 
gene differences can affect social behaviour. Social behaviour 
has its material basis in the structure and functional activity 
of the central nervous system. It would be surprising if there 
were no individual differences in the function and structure 
of the nervous system due to different combinations of genes. 
Such differences can be studied experimentally in animals. 
For instance, sports of the fruit fly can be distinguished by 
their reaction to light. Some strains of rats learn to thread 
mazes more readily than others. Extreme disorders of the 
central nervous system accompanied by extreme aberrations 
of social behaviour are known to be determined by gene 
differences in human beings. Amaurotic family idiocy is an 
example which is very firmly established. 

Studies on genetic differences which affect the social be- 
haviour of human beings are beset by two principal difficul- 
ties. Social behaviour depends upon a long process of training 
which does not begin until physical differentiation is well- 
nigh complete. Even the grosser abnormalities described 
under the general term amentia, or mental defect, are not 
always recognisable till several years after birth. Hence we 
have to exercise great care in deciding how far the manifes- 
tation of genes involved in such conditions depends upon 
factors of early development. Another difficulty resides in 
the lack of precise and reliable standards for describing social 
behaviour within the range of what we regard as normal. 

A beginning has been made with the intelligence tests of 
Binet, Terman, Burt, Spearman, and others. When people 
apply the word " intelligent " to a person, they do not mean 
something as definite as black, freckled, or intoxicated. We 
may even ask whether any useful meaning can be attached 


to the word as a description of the characteristics of human 
beings. The only way to answer such a question is to let 
different observers arrange a group of individuals in a scale 
of what they call greater or less intelligence, and to see how 
far it is possible to devise some independent test by which 
the same group can be arranged in a way which corresponds 
fairly closely with independent estimates based on personal 
impressions. This is what an intelligence test does. 

Those who are not conversant with the problem often 
assert that intelligence tests do not really measure intelligence. 
This is a survival of the scholastic delusion that words are 
more real than the functions they perform in social inter- 
course. It would be more true to say that the only precise 
meaning of the word " intelligence " is conveyed by whatever 
characteristic intelligence tests measure. In everyday speech 
the word " intelligence " is used in a variety of ways. Dean 
Inge might describe a social policy as intelligent. In that case 
I myself should probably describe it as unintelligent. An 
intelligence test does not measure anything which we mean 
by the word " intelligence " in that context. In matters affect- 
ing moral or aesthetic values Dean Inge and I would com- 
monly use the word in exactly the opposite sense. In spite of 
this, both of us sometimes use the word to draw attention to 
characteristics of human behaviour quite as definite as freckles 
or alcoholic excitement. Our description of such character- 
istics need not be affected by our social prejudices more than 
counting the number of pages in a book. It is the essence of 
the modern scientific outlook that genuine scientific know- 
ledge involves the construction of a world of public discourse 
which is ethically neutral in this sense. A large amount of 
very careful statistical analysis has been directed to find a 
scale which will absorb everything which is public in the 
ways in which people use the word " intelligent " individually. 
The tests on which this scale is based yield very constant 
results for the same individual examined on successive occa- 
sions with a short intervening period, and very constant 
results for the order within a group tested successively over a 
period of y?f3J years. 


Dubious speculations psychologists may erect upon this 
solid foundation of fact need not concern us. We have now a 
method of describing one aspect of human behaviour with 
precision and reliability. It is a method which can be passed 
from the hands of one observer to another. We can pool the 
results of intelligence tests. This we could not do if we had 
to rely on any customary scale such as teachers' estimates, 
examination results, or employers 5 testimonials. So the biolo- 
gist can investigate to what extent differences of intelligence 
are due to the fact that different children are born with 
different genes, and to what extent they are due to the fact 
that the genes manifest their effects in different surroundings 
determined by maternal health in prenatal existence, a poorly 
nourished body, over-indulgent parents, overbearing brothers 
and sisters, sympathetic teachers, and an infinite variety of 
other circumstances which distinguish the physical or social 
environment of one individual from that of another. 

Unless, as is never the case with human beings, two parents 
are both strictly pure in the genetic sense, their offspring will 
get a different equipment of genes. This is because any chro- 
mosome which a child gets from one of its parents may either 
be the chromosome which that parent received from its male 
or the one it received from its female parent. The surround- 
ings of two brothers and sisters brought up in the same family 
are more alike than those of two children belonging to 
different families at different social levels. It is therefore 
necessary to distinguish two problems which are often con- 
fused. One is how much differences within the family are 
affected by differences due to genes and differences due to 
environment. The other is how much differences between 
individuals in different social groups, such as classes or races, 
are due to one or the other. The first question can be answered 
with some assurance. When there are no differences due to 
genes, the average difference between brothers or sisters is not 
reduced by more than a half. 

This conclusion rests upon very careful statistical com- 
parison of the resemblance between identical twins and non- 
identical twins of the same sex. More than five hundred pairs 


of each type have been examined with intelligence tests. The 
investigations have been carried out in several countries, and 
they lead to substantially similar results. The test scores of 
identical twins which are derived from the same fertilised 
egg and therefore have the same genes yield an average 
difference about half as large as that of fraternal twins, who 
are not more alike genetically than ordinary brothers and 
sisters. The figure given is probably a minimum estimate of 
the influence of nurture for a reason suggested by the biblical 
narrative. Esau and Jacob are described as being physically 
different. One took to the fields, the other dwelt in tents. To 
some extent individual human beings select their own sur- 
roundings like Jacob and Esau. It is not fair to assume that 
the environment of fraternal twins differs as little as that of 
identical twins. Being more alike in other respects, identical 
twins are more likely to choose more similar surroundings, 
play together, work together, and be exposed to the same 
sources of infection. Hence a part of the greater difference 
between fraternal twins may be due to the fact that their up- 
bringing is less alike, when there are considerable physical 
differences between them. Another reason why the estimate 
given is likely to exaggerate the genetic contribution to differ- 
ences of intelligence within the family is that fraternal twins 
are more alike than ordinary brothers and sisters. Different 
birth rank accounts for appreciable differences of intelligence 
within the family. 

Between birth and the age at which formal education 
begins there exists a protracted and, it may be, highly sig- 
nificant period during which differences of social environment 
may affect the behaviour of an individual. Hence the com- 
parative constancy of a psychological index such as the In- 
telligence Quotient between four and fourteen years of age 
offers no presupposition in favour of the view that it measures 
a characteristic which is little affected by differences in the 
family environment. While relying too largely on introspec- 
tive methods and concepts of questionable validity, the 
Freudian school have performed a service to human biology 
by focussing attention on the importance of the social en- 


vironment during the years when the basic patterns of con- 
ditioned behaviour are established. 

This leads us to the second question. How far do genetic 
differences contribute to differences between individuals be- 
longing to different social groups ? Various racial and occupa- 
tional inquiries have been carried out. The conclusions drawn 
from them have rarely been warranted by the facts. Both in 
England and America the average scores hitherto recorded 
for the children of the unskilled workers are somewhat 
smaller than for the children of the professional class. The 
difference is not greater than variations which the individual 
index or intelligence quotient may register in the lifetime of 
an individual or variations associated with different birth 
rank in the same family. If differences of environment 
account for a substantial fraction of the average difference 
between brothers and sisters brought up together in the same 
family, it would not be surprising to find substantial average 
differences between groups of people living in very different 
conditions. The differences which are found are rather 
smaller than one might well expect without assuming that 
there exists much heterogeneity in the distribution of genes 
affecting intelligence. The few studies made upon orphan 
children are based on insufficient numbers to prove much. 
All the racial studies which have been undertaken so far have 
been highly selective. 

It is easy to maintain scientific accuracy in making obser- 
vations upon race differences. It is difficult to exclude social 
prejudices from the interpretation of the data. This is too 
well illustrated by the numerous and discordant comparisons 
which have been made between negroes and white Americans. 
Davenport and Steggerda, who made a comparison between 
negroes, white settlers, and hybrids in Jamaica, where the two 
races live together in comparative harmony, used the Ameri- 
can Army tests. In one-half of these the negroes excelled. In 
the other the whites obtained higher scores. The negroes did 
best in the arithmetical tests, the whites in the verbal ones. 
This is how Davenport and Steggerda interpret their results. 
" The Blacks seem to do better in simple mental arithmetic, 


and with numerical series than the Whites. ... It seems a 
plausible hypothesis, for which there is considerable support, 
that the more complicated a brain, the more numerous its 
association fibres, the less satisfactorily it performs the simple 
numerical problems which a calculating machine does so 
quickly and accurately." Experimental biologists will be in- 
terested to learn that anatomists have located the basis of 
mathematical operations with such precision. The casual 
reader may wonder why Davenport and his colleague went to 
the trouble of applying these tests, if they had satisfied them- 
selves that the large mass of evidence pointing to a high 
correlation between verbal and numerical test scores rests 
upon a misunderstanding which they do not disclose. 

The difficulty of treating group differences in a genuinely 
scientific temper will be less, when psychology can equip 
biological research with a sufficient variety of similar methods 
for the precise description of other aspects of social behaviour. 
One can assert that deaf-mutism is commoner among Jews 
than among Gentiles without incurring the charge of anti- 
Semitism. With so many diagnosable physical ailments to 
choose from, it is possible for normal people to discuss the 
occupational or racial distribution of any single disease of the 
body without assuming a tone of impudent superiority; no 
single group has the monopoly of all the virtues. When we 
turn to what is written about the social capacities of men and 
women the atmosphere changes. Some biologists are apt to 
forget that it is quite possible that the distribution of genes 
among the Scotch tends to favour a rather higher general 
level of intelligence than would be found among negroes 
educated in the same way. One can be open to be convinced 
that this is so, and retain a personal preference for generosity, 
cheerfulness, a sense of humour, vocal music without the 
accompaniment of bagpipes, and the restraint which permits 
a man to listen to a joke without explaining the point of it to 
its inventor. Time may show that there are genes which 
have something to do with the distribution of all these estim- 
able attributes. We shall then see the superior intelligence 
of the Scotch in a proper social perspective. 



The characteristics which permit human beings to co- 
operate in creating a dynamic society are very numerous. In 
the past men as a group have monopolised those occupations 
which most conspicuously call for the exercise of intelligence. 
When women first demanded freedom to compete with them 
the bulk of educated male opinion was unanimous in assert- 
ing the inferiority of their intelligence as a group. Intelli- 
gence test statistics have now shown that there is no such sex 
difference. Individual women who wish to pursue a learned 
profession can now do so. The result of this does not appear 
to be that the proportion of men and women are tending to 
become the same in all occupations. Professor Tawney is a 
sound biologist when he asserts that equality of privilege is 
the best way to ensure that the individual differences of men 
and women will find appropriate recognition. We are only 
free to judge the innate capacities of men and women when 
they themselves are free to choose the kind of environment 
in which their capacities can be realised. To adjust the activi- 
ties of individuals as far as possible to their inborn aptitudes 
it is necessary to establish a rationally planned economy with 
equality of social privileges and prestige pertaining to all 
necessary occupations, and so minimise the disposition to 
prefer the livelihood of an inefficient doctor to that of an 
expert plumber. 

The study of mental diseases that is to say, disorders of 
social behaviour invites examination from the standpoint of 
genetics just as much as diseases of the body. When a disease 
cannot be cured by controlling the environment, the only 
effective method of prevention is to prohibit the reproduction 
of persons who suffer from it and of parents who have already 
given birth to offspring who suffer from it. One class of dis- 
ease which has prompted proposals for a preventive policy of 
this kind is feeble-mindedness. Amentia, to use the more 
general term which includes the lower grades of mental de- 
fect, is an exceedingly complex group of disorders. Some 


forms are due to avoidable diseases in childhood, such as 
syphilis, encephalitis lethargica, and meningitis. Dr. Penrose, 
who has made a special study of the hereditary aspect of 
mental defect, estimates that about 1 2 per cent, of persons in 
institutions belong to this class. There is a type of amentia, 
known as mongolian idiocy, associated with certain physical 
traits to which the name is due. This seems to be due to a 
recessive gene which does not exercise any recognisable effect 
unless the unborn child is exposed to rather special conditions 
of prenatal environment. This is indicated by the fact that 
mongolian idiots usually occur at the end of a family, and are 
children of mothers who are approaching the limit of their 
child-bearing period. Mongols do not reproduce. The pro- 
portion born could be probably reduced to about a third of 
what it is now if child-bearing were restricted to the period 
between twenty-two and thirty-two years of age. 

There is a large class of amentia which is not associated 
with diseases of childhood, and is not recognisable at birth by 
any physical stigmata. This includes the higher grades of 
feeble-mindedness. Feeble-mindedness is now defined with 
reference to the requirements of intelligence tests. Indi- 
viduals are not certified as such unless they appear before the 
police court, apply for poor law relief, or are sent from the 
ordinary elementary schools to special institutions for re- 
tarded children. There is no means of estimating its preva- 
lence among the prosperous classes, where eccentricity fades 
into the diplomatic service. At present we have very little 
knowledge about the part played by heredity in feeble- 
mindedness. Haldane's analysis has shown us that it is im- 
possible to predict the results of checking the propagation of 
feeble-minded people until we know something more about 
the mode of transmission involved. It is clearly desirable to 
study the problem carefully, and to make the best of all the 
knowledge we gain. 

When we are studying animals in the laboratory we can 
arrange the conditions of an experiment so as to isolate gene 
differences or differences due to environment for separate 
investigation. Using a highly inbred stock of rats, we can 


examine the way in which body weight varies with the vita- 
min content of the food or whether they form tumours when 
the skin is treated with coal-tar derivatives. Keeping all our 
rats on the same diet, we can separate pure lines with different 
growth rates and greater or less resistance to tumours by 
selection from a heterogeneous stock. With human popula- 
tions the unaided investigator cannot do this sort of thing. 
Curiously enough, those who call themselves eugenists, the 
English equivalent of Continental Fascists, and profess as 
such to be genuinely concerned with the promotion of more 
exact knowledge about human inheritance, are foremost in 
opposing social changes which would tend to equalise the 
human environment. 

The human geneticist has to be content with recognising 
the kind of gene differences which manifest themselves over 
a wide range of environment and trying out certain alge- 
braical predictions which show us how gene differences affect 
the variability of highly modifiable characteristics. If, having 
done so, we speak of heredity or environment as more or less 
important in connection with any differences between human 
beings, our criterion of importance is relative to the historic 
environment in, which the differences themselves are 
measured. Two hundred years ago the majority of English- 
men ran the risk of smallpox infection. No doubt gene 
differences played a large part in deciding whether a par- 
ticular Englishman succumbed to the disease or escaped. No 
biologist or medical man would argue that gene differences 
provide the main reason why modern Englishmen are less 
likely to get smallpox than were their great-grandfathers or 
than Esquimaux are at the present day. 

That biologists do not always give the same answer to 
questions about heredity and feeble-mindedness is partly due 
to the fact that questions framed in everyday speech involve 
an ambiguity which arises from the changing nature of the 
human environment. If we ask, "Is amaurotic idiocy asso- 
ciated with a gene difference which manifests its presence 
throughout the whole range of conditions to which members 
of the same fraternity are normally exposed?" we can expect 


a biological answer because we have framed the question in 
biological language. No biologist who is conversant with the 
facts will hesitate to answer the question in the affirmative. 
No sensible people who know the answer would encourage a 
married couple who had produced a child with the disease to 
have more children. If we ask, "Is feeble-mindedness in- 
herited?" many biologists will answer in the affirmative. 
They will not do so because our knowledge about the gene 
differences which affect feeble-mindedness is of the same 
definite and unequivocal kind as our knowledge about amau- 
rotic idiocy. They will interpret the question in a sociological 
sense, and give it what is implicitly a sociological answer. 
The underlying assumption is that if we cannot control the 
environment we ought to take no chances with the hereditary 
aspect of the problem. There is much to be said for this, pro- 
viding it is not used as an excuse for relaxing our efforts to 
understand how to control the environment. In the course of 
millennia it is not unlikely that European communities could 
evolve a high degree of immunity to smallpox through uncon- 
trolled selective elimination of the less resistant. The African 
peoples have probably evolved their high immunity to 
malaria in this way. Thanks to human inventiveness, we have 
not had to wait several millennia to get rid of smallpox. 

There is no doubt about the concentration of mental defect 
of one kind or another in certain inbred stocks, and such 
concentration is not likely to be due entirely to the family 
environment. On the other hand, the fact that the family is 
a unit of social and physical environment, and that the an- 
cestry of a human being is a complex of environmental as 
well as genealogical relationships, is entirely consistent with 
the view that genetic differences manifest in such pedigrees 
would not necessarily manifest themselves in other situations. 
About this biologists are of two persuasions. One school holds 
that the genetic difference is all-important and that the asso- 
ciation of a hereditary taint with a depressed standard of life 
is due to social selection. Another school holds that a de- 
pressed standard of social and physical life is especially pro- 
pitious to the exhibition of gene differences which might not 


tje recognisable in favourable surroundings. A danger ot 
over-emphasising the genetic aspect of mental defect in the 
present state of knowledge is that it will discourage research 
into the rfile of the environment and so deprive the human 
geneticist of information which is essential in making a con- 
fident estimate of what selection can achieve. 

That we cannot point to any factors in the environment 
responsible for a disease or defect does not necessarily mean 
that it is associated with gene differences which manifest 
themselves throughout a wide range of environment, or that 
selection is a very effective preventive measure. The effective- 
ness of selection depends on the kind of transmission in- 
volved. If feeble-mindedness were determined in the same 
way as albinism, selection would be a very slow form of pre- 
ventive treatment. More knowledge of the part played by the 
uterine environment in determining mental defect can help 
us to unravel the way in which gene differences associated 
with mental defect are transmitted. That heredity is the 
culprit in one framework of environment is fully consistent 
with the possibility of discovering a complete cure in another. 
Heredity has condemned the Mexican salamander to lifelong 
cretinism. In dealing with land situations it has what the 
educational psychologist might call a mental age of one 
month. A single meal of ox thyroid suffices to induce it to 
complete its full development into the typical land sala- 
mander in six weeks. In that condition it may live for years. 
There is little doubt that genetic factors play some part in 
the aetiology of cancer. People do not declaim with indigna- 
tion against the expenditure of large sums upon cancer re- 
search, when such research is largely directed to display 
relevant environmental agencies such as coal-tar products. 

Discussion concerning the advisability of a policy of steril- 
isation of feeble-minded individuals has suffered greatly from 
lack of a well-balanced perspective. No doubt a rationally 
planned society in which every individual contributed his or 
her share of socially useful work would treat the feeble- 
minded group within the community as a parasitic growth 
to be exterminated with whatever efficient means scientific 


knowledge can prescribe. The sympathy with which such 
proposals are greeted at present oy many students of social 
proolems is not enhanced by the fact that they are usually 
put forward by persons who are anxious to perpetuate more 
disastrous and costly forms of social parasitism. The apathy, 
prejudice, and selfishness which permit highly gifted people 
to tolerate social arrangements wiiich may wreck: civilisation 
in our own lifetime and prevent them from making a scien- 
tific and impartial study of the immediate dangers with which 
we are beset are a greater cause for alarm than the prevalence 
of simple primary amentia. 

The recklessness with which writers of the eugenist school 
have antagonised enlightened and humane sentiment by 
attacking educational expenditure, advocating a high infan- 
tile mortality of the poor, though not of the rich, as a device 
for improving the race and demanding reduction of social 
services in general, is all the more pitiable because some of 
their proposals are capable of being considered on their own 
merits without undue emphasis on the purely economic 
aspect of the problem of mental disease. As a biologist the 
writer thinks that more might be said for than against com- 
pulsory sterilisation for certain conditions. As a citizen he 
refuses to be horrified by the present expenditure on mental 
diseases, while civilisation is burning its wheat, cotton, and 
coffee crops because it has not devised a rational system for 
controlling production and distribution of the amenities 
which science creates in such profusion. The problem of 
mental disease is worthy of earnest consideration. When the 
worst has been said about it, it is not likely to become an 
insoluble problem during our own lifetime. The problem of 
world peace may assume disastrous dimensions within the 
next decade. Great Britain spends rather more than ten times 
as much on armaments as upon all classes of mental cases. 
At any moment Western civilisation may be plunged into a 
war which will destroy it irreparably. Those who hold this 
view will regard the type of insanity which leads eugenists to 
contemplate with equanimity present expenditure on arma- 
ments as a far greater menace to civilisation than the upkeep 


of a few witless and voteless creatures in our poorhouses. 
Obviously it is not a matter of scientific judgment whether 
one chooses to deplore the fees paid to dukes as mining royal- 
ties or the fees paid to doctors for the care of the defective 
and insane. It is a matter of political taste. 



Sometime Medical Member of the Scottish Board of Health; 
Honorary Trustee, Kentucky Frontier Nursing Service 

MODERN medicine is so vast a system that it must 
have had a long history. Under the code of Hammu- 
rabi (c. 2000 B.C.) the doctors were an organised 
body of men with scales of fees for particular services to man 
and beast. This means that medicine, both as a science and 
as an art, was already old and had its traditions. In one form 
or another, as it emerges from its complicated matrix of 
primitive beliefs, medicine is consciously conceived and 
developed as one of the primary agencies for the conserva- 
tion of life; for securing to the human person the greatest 
physical and mental fitness for all the duties incident to his 
development, and for directing the improvement of the en- 
vironment throughout the whole earth. How medicine fought 
the weary fight that has ended in the relative freedom of 
today history tells us with much detail. With some definite- 
ness we can indicate the big step from magic to science; from 
the controlled philosophies of mediaevalism to the relatively 
"free philosophising" of the last hundred years; from science 
fearful of being heretical to science developed into its conse- 
quences without afterthought. This, indeed, is the problem 
of all modern science; but medicine had a leading, if not the 
chief, part in the fight, for in medicine correctness of fact is 
often a matter of lire and death, and, in the end, the fear of 
death invites the healer and conquers intolerance. The whole 
world wishes for health and strength. The wish does, indeed, 
keep magic alive; but the doctor is no longer a heretic, and 
his services are not rejected because he is thought to be a 

The attitude of the modern doctor to history is finely 
shown in Osier's Evolution of Modern Medicine. In a survey 



such as this, the discoveries, generalizations, and theories of 
medicine are made to appeal to men, not as utterances of 
authority to be obeyed, but as conclusions rationally 
grounded in observation, experiment, and verification. The 
enemies of scientific freedom are still innumerable, and they 
are still active. But informed surveys such as Osier's are the 
best guardians of scientific freedom. They give a picture of 
social human growth from the medical standpoint. 

Let us study some of the great leaders. They will take us 
at a few strides into the heart of medicine as the modern 
world knows it. In Greek medicine there were many great 
names, but by the consent of history the Father of Medicine 
is Hippocrates. In his hands medicine changed from an 
occupation to a profession. He claimed for it a distinct and 
sanctified place in human polity. He or others acting in his 
spirit placed the profession on the highest level of ethical 
sanctions. The oath of Hippocrates is still a formula for the 
spirit of honourable medicine. Some of its obligations were 
that the doctor should regard the teacher of his art as equally 
dear to him as his parents; he was to share his substance with 
him and relieve his necessities, if required; to look upon his 
offspring on the same footing as his own brothers, and to 
teach them the art, without fee or stipulation. By precept, 
lecture, and every other mode of instruction, he was to impart 
a knowledge of his own art to his own sons, and those of his 
teachers, and to disciples bound by a stipulation and oath 
according to the law of medicine, but to none others. Here 
we note that the oath is by way of being a creed of a new 
service. The doctor is to follow the system of regimen which 
according to his ability and judgment he considers of benefit 
to his patients, and abstains from whatever is deleterious and 
mischievous. Whatever in connection with his professional 
practice, or not in connection with it, he sees or hears in the 
life of men which ought not to be spoken of abroad, he will 
not divulge, as reckoning that all such should be kept secret. 
Here sound treatment is linked with confidentiality. The 
essence of the doctor's relation to his patient today is defined 


by these two points. The departure made by Hippocrates 
was thus a creative moment m European civilisation. But 
even more important for the advance of medicine was his 
method of study. He based all his work on direct observation 
of the cases; he built up case records, and on that basis rested 
his judgment of treatment or his forecast of cure. He re- 
corded the successes as well as his non-successes, "believing 
it is valuable to learn of unsuccessful experiments and to 
know the causes of their non-success/' He set aside charms, 
incantations, and astrology, as well as the irrelevancies of 
certain current philosophies. The essence of the problem was 
that to understand sickness the first study must be the sick 
person. He seems to have known the curative force of nature 
and recognised its powers to restore the normal state. The 
details of his " humours " and other points are of little conse- 
quence today; but the clearing away of irrelevancies and the 
settling down on direct study of the clinical facts are in the 
spirit of modern medicine. His method was the method of 
inductive science. Let it be recorded that Hippocrates 
(460-370 B.C.) was a figure in the great age of Athenian 

The next very great name is that of Galen (A.D. 131-201). 
He was a man of amazing versatility and originality. He left 
no part of the medicine of his day untouched. Anatomy, 
physiology, pathology, materia medica, all benefited by his 
applications of system. He wandered over the civilised 
countries of the Mediterranean and brought to medicine 
something from them all. Animal dissection, functions of 
muscles, functions of nerves, experimental paralyses by sec- 
tion of the spinal cord, anastomoses of the capillaries, the 
demonstration that an excised heart will beat outside the 
body, contractions of excised muscle independent of volition 
or nerve-supply (tonus, or Sherrington's active posture), and 
many other points were studied by Galen, and some of his 
problems are still with us. 

But instead of developing the methods of Galen's original 
researches, mankind more easily and more readily accepted 
his authority, and, in spite of his works being "a gigantic 


encyclopaedia of the knowledge of his time/' his errors, as 
well as his discoveries, dominated medicine for about 1,400 
years. " After his death European medicine remained at a 
dead level for nearly fourteen centuries " (Garrison). 

Yet here was a man who showed how to question nature 
by experiment and how to record the answer. The " Galeni- 
cal" preparations are largely to this hour the basis of our 
materia medica. Galen made a great stride forward in the 
study of the conditions of health, in the application of drugs, 
and in the consideration, both mental and physical, of the 
patient's personality. It was not his fault that, after him, 
medicine in Europe stood still. 

It is for general history to explain the failure of Europe to 
continue on the lines opened up by Galen. But medicine, if 
it soon forgot the value of direct study of nature and man, 
was not idle. The closing of the philosophical schools of 
Athens by Justinian in A.D. 529 was a symbol of some vast 
catastrophe in human thought, and medicine suffered with 
every other study. Greek ideas fled to Arabia. It is to Arabian 
scholarship that the later centuries were largely indebted for 
the restoration of classical science and literature. In medicine 
one great Arabian name stands out Avicenna. " He is the 
author of the most famous medical textbook ever written. 
It is safe to say that the Canon was a medical bible for a 
longer period than any other work " (Osier). Avicenna had a 
genius for system, and made into one the ideas of Galen and 
Aristotle. The book became an infallible oracle and, accord- 
ing to Neuberger, " an edifice of f allacy." But Avicenna was 
"at the same time statesman, teacher, philosopher, and 
literary man." Arabia developed hospitals, which were " well 
organised and were deservedly famous. No such hospital 
exists today in Cairo as that which was built by Al-Mansur 
Gilafunin 1283, The description of it by Makrizi . . . reads 
like that of a twentieth-century institution with hospital 
units" (Osier). The creation of institutions is as important 


as the discovery of principles, and we must allow for the 
larger rhythms of growing civilisations. 

Avicenna's date was 980-1037. If the seven hundred years 
after Galen must>be left blank, much thought was in process 
of elaboration, and Europe benefited by it when, in due time, 
the stream flowed back. If Averroes, a Spanish Moslem, was 
persecuted for being a pantheist, that showed that the Arabic 
mind was living and thinking and that one orthodoxy, like 
any other, takes fright at individual men. 

But, if authority remained dominant, the genius of dis- 
covery was growing. Roger Bacon (1214-1294), scholar, 
physicist, inventor, physician, and monk, wrote: "Experi- 
mental science has three great prerogatives over other 
sciences; it verifies conclusions by direct experiment; it dis- 
covers truth which they never otherwise would reach; it in- 
vestigates the course of nature and opens to us a knowledge 
of the past and of the future." This man, says Osier, "is 
mentally of our day and generation." But he stood alone. 
At the instance mainly of his fellow Franciscans, he was at 
least twice in prison, one of the periods extending over ten 
years. In the modern world this is not a recognised method 
of encouraging medical research. The fear of knowledge in 
those days must be classified as insane. Seven hundred years 
after his birth, Oxford, where he worked so long, has the 
honour of publishing many of his writings. This is as sym- 
bolic in its age as Justinian's decree of 529 A.D. The schools 
of free philosophy are open again. 

It shocks the modern mind to find that Arnold of Villa- 
nova, " a strong advocate of diet and hygiene," a learned and 
prolific writer, " was an early heretic and constantly in trouble 
with the Church, though befriended by Popes on account of 
his medical knowledge "; that Peter of Abano, known as the 
Conciliator, the author of eight of the 182 medical books 
printed before 1481, was a reputed magician and, like Arnold, 
" appears to have been several times before the Inquisition. 
Indeed, it is said that he escaped the stake by a timely death " 
(Osier). As time marched forward these rebels grew more 
numerous and bolder. But from any standpoint the story is 


a sad one. Perhaps, as Osier thinks, the concentration of the 
Western mind on the preparation for the life after death 
made men indifferent to the conditions of living in this world. 
He remarks with some acidity: "In this unfavourable 
medium for its growth science was simply disregarded, not 
in any hostile spirit, but as unnecessary." 

Paracelsus, Vesalius, Harvey these three were the giants 
of the sixteenth and seventeenth centuries. Those centuries 
" did three things in medicine shattered authority, laid the 
foundations of an accurate knowledge of the structure of the 
human body, and demonstrated how its functions should be 
studied intelligently " (Osier). Of Paracelsus (1493-1541) it is 
enough to say that, in spite of the fantastic life he led, the list 
of discoveries assigned to him in chemistry and general medi- 
cine is astonishing. He discredited Galen, whose medicines 
were largely from the plant world, and introduced the use of 
metals, such as mercury, calomel, iron, antimony, and 
others. His was the "first great revolt against the slavish 
authority of the school. . . . Paracelsus stirred the pool as 
had not been done for fifteen centuries " (Osier). " Alchemy 
is to make neither gold nor silver: its use is to make the 
supreme sciences and to direct them against disease " (Para- 

Vesalius (1514-1564) was the father of modern anatomy. It 
is not here possible to show how much this meant at the be- 
ginnings of really scientific medicine. He was " the most com- 
manding figure in European medicine after Galen and before 
Harvey. He alone made anatomy what it is today a living, 
working science " (Garrison). 

With Harvey (1578-1657) we are now well within the era 
of modern medicine. The story of his experiments and his 
discovery of the circulation is too well known to need more 
than a reference. The old theories of the heart as the centre 
for heat or the organ of intelligence had not disappeared in 
Harvey's day. His discovery and its reasoned proof may well 


mark for us the real end of the unscientific period and the 
sure beginning of the scientific. 

Let us take one name from the nineteenth century 
Claude Bernard. His work as a whole is typical of what is best 
in science. It was of this pupil that Magendie said : " You 
are a better man than I/' He developed physiology as a posi- 
tive science, ignoring mythologies of tradition and solving his 
problems by the direct method of analysis, hypothesis, and 
experiment. This was not all. He held strongly that the aim 
of physiology was to throw light on diseased conditions. On 
this ground he has been described as " the founder of experi- 
mental medicine." His broader generalisations have been a 
mental framework in the advances of modern physiology. 
And his many researches on the liver, the brain, the glands 
of " internal secretion " (his phrase), to name only these, have 
shown how complicated problems in living matter are to be 
solved. A great many specific inquiries are associated with 
his name. Garrison particularises his courses of lectures on 
experimental physiology (1855), the effect of poisonous sub- 
stances and drugs (1857), the physiology and pathology of the 
nervous system (1858), the liquids of the organism (1859), 
experimental pathology (1872), anaesthetics and asphyxia 
(1875), and operative physiology (1879). These all indicate 
that he was a man of universal interests, a Hippocrates of the 
nineteenth century. He had imagination, invention, practical 
sense, superb skill in the technique of experiment, and the 
active scepticism that stamps the scientific mind. His general 
attainments were encyclopaedic. He began life as a poet and 
dramatist, but, on advice, turned to medicine. It would be 
difficult to name anyone that combined in a greater degree 
the graces of literature with the clarities of science. 

Here, therefore, we drop history and pass to the conditions 
of our own day. 

The qualities of Hippocrates' mind are needed in every 
age. Beliefs, like diseases, may be epidemic. Sections of 


mankind become infected by false beliefs, and constitute as 
great a danger as a physical scourge. 

In 1912 a research fund for a single purpose was created 
under the first National Health Insurance Act. This led to a 
Medical Research Committee. This, in due course, and under 
the statesmanship of the late Earl of Balfour, developed into 
the Medical Research Council as it is today. This Council is 
a department under the Privy Council. This means that, as 
the Privy Council is not in the strict sense an executive de- 
partment, everything done under it applies to the whole State 
independently of any administrative department. This point 
is profoundly important constitutionally. Many departments 
in the State throw up problems for research, and some of 
them have equipment for dealing with those problems. But 
the Medical Research Council can keep touch with all other 
departments and organisations; it can co-operate with them; 
it can advise and arrange until it is not too much to say that 
the Council is the chief organising centre for research in this 
country. Here we have science at its best, organised in the 
service of the community and retrying accepted theories - 
wherever a doubt is thrown upon them. The nature of its 
immense activities can be gauged from the scores of elaborate 
reports and surveys issued under its direction. It is the organ- 
ising centre for hundreds of researches. It has its special 
committees covering the whole area of medical problems; it 
has succeeded in gathering to itself capable and original men, 
and its organisation is so adaptable that all serious research 
in the country receives encouragement and assistance. The 
Council is in touch with the laboratories of the medical and 
scientific schools, both in this country and abroad. 

The formula adopted by His Majesty's Government to 
define the field of medical research, work to which an annual 
Parliamentary grant in aid is made, is as follows : " Medical 
research deals with the proper development and the right use 
of the human body in all conditions of activity and environ- 
ment, as well as with its protection from disease and accident 


and its repair." In a discourse at the Royal Institution on 
" The Scope and Needs of Medical Research," the late Sir 
Walter M. Fletcher analysed this comprehensive formula. It 
covers inheritance and nutrition, genetics, energy values of 
diet, sleep, relation of climate to bodily activity, innumer- 
able problems of industrial life, the optimum of work, the 
optimum pauses, hours of work heavy or light, shift systems, 
the effects of monotony in repetitive work, vocational guid- 
ance and selection, study of movements, posture, physique, 
prevention and palliation of disease, faults of environment, 
parasitic enemies, vitamins, the welter of diseases like 
typhoid, sleeping sickness, malaria, and a multitude of 
others. The formula, it is clear, covers practically the whole 
of the uses of the body and the dangers it is exposed to; 
social as well as individual physiology; the physics, chemis- 
try, and pathology of the environment of all the different 
climates; and, in a word, all that affects for better or worse 
the efficiency of the human organism in all its relations. 

Our formula covers only the British programme, but it is 
wide enough to cover the researches of all other countries, 
and among the most useful reports are the summaries of work 
done all over the world in fields of which this formula may 
be taken as the major premise. It must not be supposed that 
the Medical Research Council is an exclusive organisation. 
On the contrary, it aims at stimulating the innumerable re- 
searches of the schools of medicine and science in this 
country and also at collaboration with the schools abroad. 

The researches conducted in the schools of tropical medi- 
cine show how the great tropical diseases malaria, yellow 
fever, cholera, and plague are handled. It is common know- 
ledge that, by the extirpation of yellow fever and malaria, the 
area of the Panama Canal was, as one American doctor has 
said, converted from a nest of diseases into a health resort. 

In these twenty years or so the discoveries of Sir Frederick 
Gowland Hopkins and fellow-workers of other countries on 
food alone, have transformed the whole theory of diet and 
established a new scientific groundwork for the investigation 



of nutrition. The discovery of the accessory food factors, or 
vitamins, ranks among the great discoveries of history. After 
ten years the Council has issued a second edition of its survey 
of present knowledge in this field. The survey includes 
thousands of references to work done. It is hardly necessary 
even to name the vitamins whose properties are here detailed, 
but they cover problems of growth, reproduction, defence 
against infection, specific diseases like rickets, beri-beri (a 
nervous affection), scurvy, dermatitis, pellagra, and many 
other nutritional conditions. The number of vitamins now 
known or suspected is about ten. Their partial isolation in- 
volves the most refined methods of physical and biological 
chemistry. The diseases named are regarded, some with 
certainty, others provisionally, as " deficiency diseases." The 
masses of facts determined by experiment are available for 
application to the human organism. It is only a matter of 
time and administration for diseases like rickets, beri-beri, 
scurvy, and many related affections of nutrition to disappear 
from the human race. Of vitamin D, known as Calciferol, 
the anti-rachitic vitamin, Sir Walter Fletcher says : " In pure 
form this has an almost incredible biological potency. A 
single ounce of it would suffice to give a full daily ration for 
a million growing children." This substance has been isolated 
in pure crystalline form. The others are used in the form of 
concentrates. The chief practical result for medicine is that 
all those substances can now be standardised, and the 
administrator will in time have to persuade the community 
to secure that supplies of every such essential substance shall 
be available for every expectant mother and every child born. 

Within the last half-century or so drug therapy has been 
greatly simplified. The drag-net prescriptions of previous 
days have largely disappeared. The refinements of pharma- 
ceutical science have ended in the greatest precision of 
dosage. The resources of modern chemistry have been 
applied to the forming of new drugs of endless variety. These 
are all tested biologically and clinically before they go on 


the market. They are known to have definite effects on defi- 
nite organisms; the guesswork sinks to a minimum. The 
science of pharmacology keeps whole sections of the medical 
and pharmaceutical professions in constant activity. The 
minuteness of experiment and careful verification exceed 
anything known to the past. The British Pharmacopoeia of 
1932 is not simply a new edition of an old document. It 
arose out of the work of a special Pharmacopoeia Commission, 
who heard experts in physiology, in pharmacology, in phar- 
macy, and in therapeutics. It is a handbook of tested materials 
and includes whole departments unknown to previous 

There are several therapeutic substances that must be 
tested biologically. These include anti-rachitic vitamins 
(vitamin D), anti-dysentery serum, diphtheria anti-toxin, gas- 
gangrene anti-toxin, tetanus anti-toxin, insulin, old tuber- 
culin, pituitary (posterior lobe) extract, and a series of special 
drugs such as digitalis, strophanthus, and certain arsenical 
drugs used in the treatment of syphilis. For all these the tests 
are standardised by international agreement. The manufac- 
turers are subject to the most minute regulations. In Great 
Britain their products must be submitted to the National 
Institute of Research and passed by it before being put on 
the market. These extraordinarily severe restrictions are due 
to the extreme delicacy of the drugs, their liability to go 
wrong, their great potency, and their immense value in the 
treatment of disease. The international control was arranged 
through the Health Section of the League of Nations. The 
result is that the communities can rely on obtaining correct 
material correctly tested. This is a medical departure of the 
first magnitude. Other substances of the same class will, in 
time, find their place under the regulations. Meanwhile, the 
world is protected so far as correct scientific technique can 
protect it. 

History shows that food has played a part in therapeutics 
for centuries. But in the last generation two special dis- 


coveries have compelled a revisal of all food values : these are 
the discovery of vitamins and, in particular, the discovery of 
insulin. Perhaps in this regard the acid-base equilibrium of 
the blood should be reckoned as a fundamental guide to 
correct diet. Correct diet is the diet that maintains nutrition 
without producing any deficiency disease. Perhaps, too, we 
may add the discovery that liver is of special value in some 

Insulin is the secretion of special gland cells within the 
pancreas. Its absence involves diabetes mellitus; its presence 
prevents diabetes mellitus. Hitherto the treatment of diabetes 
has had to rest mainly on modifications of diet, in particular 
the amount of carbo-hydrate consumed. Now that insulin is 
available in treatment, the carbo-hydrate diet and the 
amount of insulin are adjusted to each other until, by the 
combination, the amount of sugar in the blood is maintained 
at a correct percentage. Roughly, it may almost be said that 
no one need now die of diabetes. 

But correct diet for other morbid conditions has benefited 
with the experience in diabetes. The diet must produce 
enough heat and it must have its complement of vitamins. 
The restudy of foods from this point of view has ended in 
many radical modifications. It may now be said that, apart 
from the special diet for particular diseases, the maintenance 
of the body in health demands specially constructed diets 
correctly cooked. This is a very large field, but it is of grow- 
ing importance in the treatment of disease and the main- 
tenance of health. 

Modern methods of diagnosis have been greatly developed 
in the last generation. They include improved mechanisms 
such as the polygraph and electro-cardiograph to indicate the 
cycle of the heart; the classification and staining of the blood 
cells as they alter in particular diseases like pneumonia; 
tuberculin testing of the organism for active tuberculosis; 
chemical testing of the blood for disturbances of the acid-base 
equilibrium; the Widal test for typhoid fever; susceptibility 


tests for diphtheria and scarlet fever; X-ray examinations for 
conditions of internal organs; and many other tests, some 
older, some more recent. All these tests have been based on 
prolonged experiment and experience. But every day brings 
forth more ways of making diagnosis easier and surer. 

New methods of treatment keep pouring out of the labora- 
tories and the clinics. The large textbooks and encyclopaedias 
are now supplemented by books showing the " advances " in 
diagnosis and treatment. Every six months may produce a 
body of new researches on twenty different lines. The docu- 
mentations of these volumes are incredibly extensive. It is, 
therefore, useless to offer any further detail in this sketch. 
The general principles long established are, of course, 
honoured rest in pain, cooling of the body, clean air, light. 
It is common to see acute illnesses like measles, whooping 
cough, pneumonia, pulmonary tuberculosis, and others 
treated in the open air and sunlight. This is a revolution 
compared with even a few years ago. There are also the 
specific treatments for infectious diseases. Strange discoveries 
never cease; for instance, a benign form of malaria is now 
largely used for the treatment of general paralysis of the 
insane, which is due to syphilis. Many infections are still a 
mystery; their viruses we must not say micro-organisms 
are too small to be seen with the ordinary microscope or to 
be strained out by the finest known filter; they are "filter- 
passers." But the laboratories and the clinics are busy with 
them. Treatment by special drugs has reached a stage of 
great simplification and refinement. A modern marvel is the 
treatment of syphilis by arsenical preparations. Some twenty 
years ago this disease was practically " incurable." Today it 
is curable, given the time and the patience dictated by its 
peculiar natural history. And that principle applies to all the 
infections : the treatments are adjusted to the natural history 
of the germ. Even with the great diseases cholera, plague, 
malaria, and leprosy the methods of treatment are improv- 
ing from year to year, and the conquest of them all is a 


matter of time. In any well-equipped hospital the treatment 
of drugs is a well-organised system, but this is supplemented 
by facilities for massage, remedial gymnastics, X-ray applica- 
tions, deep therapy apparatus for cancer, radium, diathermy, 
electric baths, ionisation, foam baths, hot and cold applica- 
tions of many varieties, light, ultra-violet rays. The rest 
methods in treating tuberculosis are full or ingenuities. 
Needless to say, the inventions applied in surgery are without 
end. Outside the schools, there are all the tested practices of 
the health resorts. 

The doctor and the nurse have for ages been a working 
team. But modern medicine includes, also, health visitors, 
almoners, special social investigators, skilled lay assistants of 
many varieties, as in eye diseases, ear diseases, surgical appli- 
ances, rest jackets, plaster-work, and the like. Of these lay 
services, one of the most important is the social investigator. 
In 1909, Richard C. Cabot, M.D., published a small book on 
Social Service and the Art of Healing. He found that, par- 
ticularly in the out-patient departments, the prescription of 
medicines, say, for some form of dyspepsia was largely use- 
less because many patients were living in social conditions 
that aggravated or caused the trouble. Out of these considera- 
tions arose the whole system of social services now attached 
to the large hospitals. Social workers of the right disposition 
and trained in the right way make inquiry regarding the 
cases allotted to them where it is supposed that a nervous 
factor, or a worry factor, or social difficulties of some sort, 
may be involved. Confidential reports are made. The patient 
is put in touch with the appropriate relief services. The dys- 
pepsia or the neurasthenia disappears rapidly because the 
social causes of the disease are removed. This means that the 
doctor is treating, not an abstract disease, but a sick person in 
the concrete conditions of life. The system is spreading in 
every community. 


Public health includes the hygiene of the environment and 
the management of infectious diseases. In the modern de- 
velopments it covers also the provision for maternity and 
child welfare services. In the broad sense it must cover also 
the provision for old age, feeble-minded, lunacy, and the dis- 
eases incident to poverty. All these are within the control of 
the public health authorities. To this may be added school 
health administration, which involves the examination of 
millions of school children. There are still other items, but 
space forbids further enumeration. All these activities are 
preventive; but there is a special use for prevention in the 
treatment of individual persons suffering from general dis- 
eases. This form of prevention has, as yet, gained little mo- 
mentum in medical education or in treatment. But a type of 
what we mean is the assessment of fitness necessary for civil 
or military occupations; for here the problem is not what 
disease does a man suffer from, but whether he suffers from 
any disease, and if he is healthy, what work is he equal to. In 
many of the great services of civil life the assessment of fit- 
ness is the primary purpose of medical examination. But in 
the ordinary work of medicine the doctor is called in only 
when the patient is sick. For the assessment of psycho- 
physical fitness, however, the patient's condition must be 
examined by skilled persons, whether illness is present or not. 
The insurance companies are all guarded by minute medical 
examination. But this class of preventive work has not yet 
found its way in any great degree into the teaching schools. 
This, however, is a class of work that is developing rapidly 
outside and will ultimately become the predominant work of 
the medical profession. For the moment this type of preven- 
tion is generating special clinics, such as heart clinics, of 
which, in 1925, there were forty-seven (with some 12,000 
clients) in New York City alone. It is also generating asso- 
ciations for making periodic medical examinations of 
members, independently of their being ill. This periodic 
"vetting" is said to improve the life expectation of the 


At no time in the history of this country has so much 
attention been given to the study of psychology. Before the 
War the study of insanity had behind it a long history. But 
the War gave an immense impulse to the study, not of in- 
sanity only, but of psycho-neurosis in every variety and 
degree. Even before the War feeble-mindedness had already 
established a claim on the public authorities, but since the 
War this study also has gone rapidly forward. For the acute 
insanities provision has been made for several generations in 
large asylums. The term " asylum " is now dropped, and 
those institutions are mental hospitals. This is not a mere 
verbal difference, for the study of insanity has itself changed. 
The insanities are of many varieties; some of them are due 
to toxins, others to degenerations, others to mere functional 
exaggeration of physiological conditions, and others are inci- 
dental to certain diseases. But through the whole field the 
insanities are studied as a compound study; that is, they in- 
volve both the mind and the body. No matter what view is 
taken of the relation of mind and body, whether the body is 
assumed to be possessed by a special substance called mind 
or whether the mind-body is to be regarded as a single sub- 
stance with two aspects, or whether we look at it more broadly 
as two series of events running parallel with each other in all 
cases the mind-body has to be regarded as a unity. To attempt 
to treat the body without considering the mind or to treat the 
mind without considering the body is equally futile. The 
human personality must be treated from both standpoints at 
once. When the patient becomes insane the nutrition of the 
whole body is affected. Reversely, when the body is affected 
by certain toxins the nervous system may undergo degenera- 
tion and the mental symptoms may be a form of insanity. 
For instance, in pneumonia it is common to have delirium. 
Similarly with typhus fever and many other fevers. When 
the toxin is eliminated the mental symptoms go. It is now 
th$ custom for the expert in insanity to test the organism for 
possible poisons; for instance, the toxins of specific fevers. In 
these cases the mental symptoms are really a delirium due to 
poison. On the other hand, a primary insanity may be due to 


degeneration of the brain. The symptoms and treatment are 
wholly different. But in all cases the body or mind or the 
mind-body must be regarded as a unity. 

Hitherto, in this sketch, we have dealt only with the 
physical side. But in the modern curriculum provision is 
made for the special study of normal psychology, morbid 
psychology in all its phases, and the psychology of acute in- 
sanity. But modern treatment tends more and more to search 
out the very early cases, where, perhaps, only some slight 
functional signs indicate instability. These are treated by 
relevant physical methods baths, massage, and other appli- 
cations and, treated thus early, mind and body may be 
restored to normal. The professor of psychiatry covers the 
whole range from passing obsessions up to the major insani- 
ties. But, above all, he is in a position to show how funda- 
mentally important it is never to forget either side of the 
human organism. As Bain said in his Mind and Body over 
fifty years ago : " The mind is destined to be a double study 
to conjoin the mental philosopher with the physical philo- 
sopher; and the momentary glimpse of Aristotle is at last 
converted into a clear and steady vision." An old and learned 
medical friend, who had shown heroic fortitude through 
years of suffering, once said to me in a voice of pa? Ion : 
"What I need is a man that can grasp my whole person- 
ality." That is the right standpoint for the educated 
physician. Physical health and mental health are aspects of 
the same problem, and the man that neglects either will fail 
in both. 

It is common and easy to say that " progress " is an illlusion 
of the nineteenth century. But in every section of medicine 
progress has a definite meaning and, as a rule, can be tested. 
For instance, if the average duration of life has become 
greater in a given period, it is right to ask whether medicine 
has had a part in this extension. Fortunately, by the elabora- 
tions of the systems of insurance this problem can be dealt 
with quantitatively. The birth-rates and death-rates are now 


available in every civilised society. The numbers living at 
given ages are carefully compiled from the census. The 
numbers living and the numbers dying can be so arranged 
as to show whether one period is more favourable to long 
living than another. Briefly, the life-table can tell us the 
average expectation of life or the mean duration of life. And 
this life-table is scientifically constructed out of the actual 
societies of living and dying people. It is not an abstraction; 
it is a measure of a concrete phenomenon. If the average 
expectation of life is proved to be greater in one generation 
than in another, and if the increased duration is shown to be 
due to the better control of given diseases, medicine may 
claim a share in the effect. And the concept of the life-table 
has been applied scientifically on so great a scale that the life- 
table is a reliable measure of progress. The insurance com- 
panies construct their benefits on the basis of life'-tables. 
It may be said, generally, that in the last few decades 
the expectation of life in civilised countries has increased 

The following illustrations of increased expectations are 
taken from Health and Wealth, by Louis I. Dublin, Ph.D. : 

In England and Wales in period 1828-1854 the expectation 
of life at birth was 40-88; in period 1920-1922 it was 56-95. 
In Scot^nd, 1861-1870, it was 42*09; at 1921 it was 54*71. In 
France, 1817-1831, it was 39*55; 1908-1913 it was 50*46. In 
Italy, 1876-1887, it was 35*25; in 1910-1912 it was 47*38. In 
Sweden, 1816-1840, it was 41*53; in 1911-1920 it was 56-99. 
In Denmark, 1835-1844, it was 43*65; at 1921-1925, 61-10. In 
the United States, 1901, it was 49*24; in 1926, 57*74. 

Thus in England and Wales there has "been a gain of 
sixteen years in the interval of eight decades/' In a similar 
period Denmark shows a gain of seventeen and a half years. 
Massachusetts showed a gain of fifteen years in sixty-five 
calendar years. 

Tuberculosis is declining rapidly, but some of the diseases 
of middle and advanced age are not. The special analyses of 
a great insurance company's claims tell us definitely which 
diseases are most deadly. Dr. Dublin is thus able to make 


reasonable forecasts of the probable extension of life in the 
coming generations. 

The medical curriculum has two primary purposes : first, 
to maintain the scientific groundwork of medicine by pro- 
viding recruits for teaching and for research; second, to 
maintain the numbers of trained doctors necessary to provide 
medical diagnosis and treatment for the community. 

The curriculum, therefore, must include discipline in 
the fundamental sciences of physics, chemistry, biology, 
anatomy, and physiology. It must equip the student with a 
knowledge of diseases by courses in pathology and bacteri- 
ology. It must teach him how to apply his knowledge in 
practice by courses in pharmacology, therapeutics, systematic 
medicine, clinical medicine, systematic surgery, clinical 
surgery, midwifery and diseases of women, public health, 
medical jurisprudence, and in many other subsidiary appli- 
cations of the sciences to practical diagnosis and treatment. 
At one of the chief medical schools the courses, long and 
short, number forty-three. These are spread over five years. 
In some schools, to prevent over-pressure in any single term, 
the course has been extended to six years. 

These courses are the ordinary obligatory curriculum for 
all graduates. The schools also provide special courses for 
diplomas and certificates. The curriculum must be such as to 
furnish the proper instruction for all grades of medical prac- 
titioner. These grades include private practice, National 
Health Insurance practice, public health service, school health 
service, Army, Navy, and Air Force services, as well as 
specialists of many other orders. 

Once registered on the Medical Register, the graduate be- 
comes a qualified medical practitioner and passes under the 
statutory control of the General Medical Council. The 
Council may remove him from the register for certain classes 
of crime and also for conduct that, on inquiry, it finds to be 


infamous conduct in a professional respect. He is free to 
practise any theory of medicine he chooses, no matter how 
far he diverges from accepted ideas. The holding or practis- 
ing of any special theory of medicine is not, by itself, a 
ground for removal from the register. 

In Britain the Medical Register began in 1858. From that 
time to January i, 1932, 108,629 names were entered on the 
register. At the beginning of 1932 there were remaining on 
the register 55,604 names. The Medical Register for Great 
Britain and Ireland (including the colonial and foreign lists) 
contains a list corrected up to the beginning of each year of 
all those entitled to practise in terms of British registration. 

Yesterday, medicine was concerned with a searching for 
origins and a fumbling approach to a method. Today medi- 
cine is a vast system of ideas, discoveries, generalisations, 
theories, and practical proposals, all under discussion by 
thousands of experts. Tomorrow, it will be a problem of how 
to relate the imperatives generated in the course of history 
to the working values of life in the growing society of the 
future. How shall we formulate some of these imperatives? 
In our condensed sketch we have indicated the channels that 
have been formed for the energies of medical men in the 
conduct of their duty. But, after all, the world does not exist 
merely to get its sick persons cured. There must be some 
larger purpose. Medicine comes very close to the key-points 
of life. The healing of the sick has always and everywhere 
been accepted as among the highest aims of personal en- 
deavour. In the modern world the private doctor is " called 
in " when a member of the family is ill. It is assumed that he 
is intellectually and morally qualified to have access to the 
intimate life of family or person. This is a fact of tremendous 
importance. It means that in the course of social evolution it 
has been found that the parents of children or the children 
themselves are open to innumerable afflictions that they do 
not understand and cannot meet. The doctor is the special 
servant created by the social needs to tackle and handle to a 


good issue wherever possible, but in any case to handle, the 
afflictions that trouble the families, lie is, therefore, an 
officer specially trained to cure where disease is present, to 
advise where conditions less than disease are present, so to 
guide the family that the father and mother are enabled, 
with him, to fight disease, that suffering may be relieved and 
death postponed. 

In the presentation of medicine given above the " sanctions 
of medicine " were left to the last. They are the name for the 
organisation set up by Parliament to keep before every 
member of the medical profession the lines of honourable 
social conduct. Every year brings its quota of culprits. The 
offences vary from something relatively trifling to offences of 
the grossest order. And the investigation of these offences is 
not confined to an individual medical man acting as the 
accepted doctor of a family, but to the same man acting in 
his public capacity as a notifier of diseases, as a writer of cer- 
tificates, as a person legally responsible for declaring the 
causes of death, as an insurance practitioner responsible for 
authorising the outlay of money on sickness, and he has many 
other official duties flowing from the fact of his being a 
qualified medical practitioner. Then, if we look to the public 
service, the medical officer of health has entry into every 
home when the public health is endangered by the occur- 
rence of infection, or when the conditions of housing, or 
general environment, or occupation are injurious to health. 
Whole Acts of Parliament are loaded with the details placed 
under his executive. 

Out of these special relations of the doctor to the com- 
munity certain imperatives of medicine have arisen. Today 
our civilisation speaks to the doctor somewhat in these terms : 
"You shall not kill. You shall answer the call of sickness. 
You shall regard the sick man as already within the shadow 
of death and so in a place apart and to be treated with under- 
standing and sympathy. You shall devote to him with your 
whole heart the knowledge and skill you have acquired. No 
matter whether he has been guilty of crime or anti-social 
conduct of any kind, you shall deal with him only as a sick 


man to be saved from disablement or death. You shall not 
forget that, in the privileged position accorded to you and 
subject to the requirements of public justice, you are under 
obligation to maintain social confidence as between man and 
man. You shall fulfil the conditions of honourable service as 
these are set forth in the laws devised for your profession." 

In the execution of these imperatives a man finds himself 
under strong ethical tension. To him no medical duty can 
ever be indifferent. He finds, each in his own measure, that 
the practice of medicine is the practice of life. Every hour is 
" a bringer of new things." From a trifle that may be ended 
with a word he may pass to a tragic emergency. He may 
have to face serious danger or even death in his dealings with 
the unconquered diseases at home or abroad. He leads a life 
that is never free from anxiety. To the varieties of pathetic 
experience there is no limit, and the doctor, if he preserves 
character at all, attains to a ripeness of sympathy and a social 
insight that give him an exceptional place in the service 
of man. 

This is enough to suggest how closely the medical man 
lives to the values of life. He is in a very literal sense the 
friend of man. From the student thinking only of cases, he 
grows into the ethical philosopher, thinking only of persons. 
To this end medical experience is highly favourable; for, on 
the one side, the doctor is trained in the science of medicine, 
and, on the other, he is always faced with problems of human 
conduct. Medicine, both as a science and as an art, is thus 
peculiarly rich in the higher motives to action; for science is 
itself a primary value and the concrete life of the family is 
the genetic point of society. 

Ever since Darwin propounded his theory of the origin of 
species by natural selection there have not been wanting 
critics to say that preservation of the unfit necessarily involves 
the deterioration of the race. The logical inference of this 
hard doctrine is that the gross conditions of nature, conditions 
that are largely artificial in modern life, should be allowed to 


work their full effect, and this is assumed to be the killing off 
of weaklings. From this standpoint medicine is one of the 
worst sinners; for undoubtedly the extirpation of diseases 
and the prevention of disease in individuals do have the 
result that more people with certain defects are kept alive 
longer than if our hideously constructed towns, our dirty ill- 
ventilated houses, our imperfectly constructed factories, and 
the multitude of other unhygienic conditions, were left to 
their natural course. Yet the criticism is rather superficial. It 
assumes that the indiscriminating attack of those lethal con- 
ditions is to be regarded as "natural" selection, when in 
reality they are the products of human ignorance and care- 

Let us look at the facts from the other end. The question 
we have to ask ourselves is something like this : " Is it a good 
thing that everybody should be as healthy as his inherited 
endowment permits him to be; as physically strong, as 
mentally alert, as ethically competent to face the day's duty? 
Shall we have a better society if reasonable care is taken to 
see that the child is born into worthy conditions; that he is 
well nourished in his first three years, the period of his most 
rapid growth; that, in his transit from infancy to adolescence, 
he shall have access to air, light, and exercise, that he may 
attain smoothly and naturally to his best physiological 
normal, and that, when he comes to take his place in the 
adult community, he shall do so with good teeth, good eyes, 
good ears, good muscular development, good heart and 
lungs, and good organs generally?" 

To achieve this end means that the whole forces of the 
community have to be concentrated on the removal of evil 
conditions, on the control of disease, on the maintenance of 
health, on the educational discipline of individuals of all 
ages, on definite programmes of work adjusted to the special 
conditions of each community. To assume that the products 
of human inefficiency are conditions of nature is not legiti- 
mate reasoning. The environment itself is in a state of con- 
stant evolution and involves infinitely subtle readjustments 
of the organism. When the conditions of a growing society 


are as perfect as man's energy can make them, it will be time 
enough to raise the question of letting the weaklings die. 

What, then, is the real question? It is surely this : that, by 
the control now partially established over infectious disease, 
early deaths have fallen and lives are longer. The same result 
follows from the better treatment of all disease. The effect of 
these medical activities is an extended expectation of life. 
The result is that, as the working capacity lessens in advanced 
life, the burden on the community increases. This is not a 
reason for throwing persons of impaired vitality on the scrap- 
heap. Rather it is a reason for discovering fresh readjust- 
ments of labour to fit the impaired energies and economic 
readjustments to enable the community to keep the older 
persons in productive activity. In this problem we are only 
at the very beginning. The old age pension at seventy is one 
method tested in this country; another is the pension based 
on contributory insurance; and a third is the lessening of the 
burden of medical service by the increasing transfer of indi- 
vidual medical treatment to the larger communal units or 
even to the State itself. In all this there is a perpetual re- 
adjustment from day to day and year to year of the organism 
to its environment and of the environment to the organism 
these two being always and everywhere supplementary to 
each other. If by preventing rheumatism we reduce early 
heart disease, we are, at a stroke, able to keep a greater pro- 
portion of young people fit for the work of industry. If by 
early care of mild heart affections we enable the man of 
middle age to add many years of work to his record, we are 
really maintaining the efficiency of the community as a 
whole. When, on the long run, heart disease asserts itself in 
the older ages, we are then faced with the economic problems 
of subsistence. When technical " old age " supervenes, civil- 
isation says we shall provide for it. 

Here medicine leads us into the heart of problems that 
affect the whole evolution of society. So far as fitness can be 
maintained, medicine is under an ethical obligation to main- 
tain it. The problems following on this are problems for 
statesmanship, and, as only a few experiments have yet been 


tried, it is too early to say that medicine is indirectly pro- 
ducing any deterioration of society. 

Eugenics is not an affair of medicine exclusively; yet it has 
medical relations. For the many specific affections that end 
in hereditary disabilities have to be investigated medically. 
All we need say here is that, by many institutions and much 
individual treatment, the effects of inheritable feeble-minded- 
ness, to take only one instance, are largely prevented. The 
methods of segregation are spreading. It is not necessary here 
to restate the modern doctrines of inheritance. It is enough 
to say that in their latest interpretation those doctrines are 
shown to be not inconsistent with the work of preventive 

The control of life in specific ways leads naturally to the 
larger issue : How far can medicine assist us in the control of 
life generally? Even from the details of our brief sketch it is 
obvious that the superintendence of growth is getting closer 
and closer to the real problem of social evolution. Through 
a hundred channels the science and art of medicine may 
become an effective guide in the control of life. Here we 
pass beyond the gross work of preventing infection, mending 
the disabled, and helping the diseases of the individual. The 
problem before us is no longer a problem of disease. We may 
assume that, sooner or later, much disease will disappear 
from the community; but even when all preventable disease 
is prevented, both in the community and in the life of the 
individual, the fundamental problem emerges namely, the 
problem of continued good nutrition. Men, women, and 
children must be fed. The modern revelations of medicine 
are teaching us more and more in detail how to feed them 
correctly. This is a problem that can never be finally solved 
so long as the human race produces new children. But the 
solution will involve the energies of all the doctors, of the 
hygienic laymen, and of the services organised for the main- 
tenance of health, physical and mental. At the moment this 



is a far-off ideal, but the advances of the last fifty years are 
full of hope for the future. 

There are the many problems as yet unsolved; for example, 
cancer and its congeners. All we need say is that the surgeons 
work wonders by the excision of early cancer, and the re- 
search departments everywhere are getting closer and closer 
to the problem. Any hour may reveal the secret. Meanwhile 
the doctor must do his best, in this as in other incurable 
conditions, to reduce suffering, to make the bed of death as 
easy as possible for the hopeless mind, and to keep touch 
with the best that is known and done. 

In the growth of society medicine is playing a very great 
part, and the future will find it playing a part still greater. 
The set purpose of medicine, to create a healthy community 
and so establish general happiness on a relatively stable foun- 
dation, seems here to coincide with the end of social ethics. If 
what I have said of the rich motives of the medical profession 
be true, even in part, the doctor is exceptionally qualified to 
maintain a sane outlook on social evolution and the states- 
manship needed to direct it. Even in the ultimate problem 
of ethics namely, the reconciliation of self-interest and the 
interest of the community the medical man is well trained. 
His sympathies are likely to be fully developed, and every 
day he has to postpone his personal pleasure to his public 
duty. As Bain, in arguing the general case, says : " We are 
under a divided dominion; the best of us are always faithful 
to Society; the worst cannot entirely throw off allegiance. 
* Am I not a man and a brother'?' is the full expression of 
Homo sum!' This is the main postulate of social ethics and 
offers a major premise for the art of medicine. 


By R. R. MARETT, M.A., D.Sc. 

Rector of Exeter College ; Reader in Social Anthropology, 
University of Oxford 

THE anthropologist premises that mankind should be 
taught to take a broad and impartial view o itself. 
History has always professed to prepare the ground 
for such a survey, but has remained essentially a history of 
civilization, and almost exclusively of Western civilization. 
Reasons good as well as bad could be urged for this attitude. 
The worst possible reason would be that we are the human 
beings whose private affairs matter most. The best reason, 
perhaps, would be that authentic history must rest on written 
records. But, to treat the latter argument alone seriously, the 
archaeologist is certainly not going to allow that what he 
reveals by means of the spade is devoid of historical meaning. 
He might even hint that one was likely to unearth fewer lies 
in this way than by digging them out of books. Again, 
whereas history is clearly obliged to carry the past down to 
the present, the historian of civilization notoriously fails to 
do this effectively, because if he stands too near to matters of 
wide bearing and interest as, for instance, the recent Great 
War he straightway gets the facts out of focus. But the 
ethnographer, the student of primitive folk, whose history is 
more or less all in the present, claims that he is better qualified 
to see his facts in fair perspective; since in the first place they 
are themselves on a smaller scale, and in the next place the 
difference in culture between observer and observed produces 
on the mind's eye an effect of concentration not unlike that 
caused by distance in time. Ancient prehistory and modern 
prehistory, as the French term them, must have their weight, 
whether it be worth much or little, together with the history 
of the peoples who possess a literary past. The anthropologist 



aims at a more universal outlook than the student in any 
other branch of the humanities. 

Something more, however, must be added before his real 
position is disclosed. In order to satisfy the anthropologist, 
this universal history of mankind must be construed as a 
natural history. A natural history of religion must by ab- 
straction disregard altogether the possibility that the religion 
may be revealed. Natural here means biological, and bio- 
logical in its turn means evolutionary. Anthropology is among 
the biological sciences and accepts their naturalistic and evo- 
lutionary outlook. Hence in setting out to compose a uni- 
versal history of man it takes over from general biology two 
main postulates. The first of these is that there is strict natal 
continuity between all the forms of life, and consequently 
that the appearance of our species on this earth was due to no 
special creation, but to what the geneticist knows as muta- 
tions. The second is that Man belongs to the class of organ- 
isms that is integrating or evolving; in other words, that from 
its first appearance onwards in time the human race has ex- 
perienced no Fall of Man, but on the whole has been grow- 
ing more highly organized, primarily as regards its bodily 
and mental constitution, and secondarily in respect to the cul- 
ture the set of habits resulting from this change in the 
hereditary nature. On both these points our fathers, taking 
the Genesis story at its face value, believed differently. Now, 
although science is bound to no creed, modern anthropology 
holds so firmly to these two working assumptions that here it 
would not be worth while to discuss their validity; for, if they 
go, anthropology goes too, and we must begin all over again. 

If, then, so late as the year 1600 Giordano Bruno went to 
the stake for writing, " With Pythagoras I regard the Earth 
as a star," the anthropologist may yet have to suffer persecu- 
tion for saying, " With Aristotle I regard Man as an animal." 
Nevertheless, the doctrine that Mankind is not part of the 
order of Nature is surely too unreasonable to prevail. We 
palpably have bodies besides souls, though the philosopher is 
mystified by the soul's need of a body; for he prefers to put 
he problem of their interconnection in this order rather than, 


with the naturalist, the other way round. Astronomy has 
ceased to be geocentric, but philosophy remains anthro- 
pocentric. It ihsisfs IHat mind is the measure of all things, 
and reminds the natural sciences that they are expressions of 
mind, and hence that their Nature is a sort of mental pro- 
jection. This is a point of view which the sciences have only 
very recently shown any inclination to accept. As long as the 
Newtonian physics was unchallenged, matter appeared cap- 
able of walking through mind, as Tiresias was fabled to do 
when allowed to retain his bodily substance among the ghosts 
in Hades. The physical categories can now boast no such 
coarse advantage over the spiritual. For a cosmo-physicist a 
radically indeterminate universe is a possibility to be seriously 
contemplated. To the old-fashioned scientist such a thought 
was shocking. It is shocking, too, to some philosophers. There 
are philosophical absolutists who have difficulty in rebutting 
the charge that they are determinists. Both schools of thought 
the Newtonian physicists and the Hegelian metaphysicians 
presume a commensurable order of things. If Nature in its 
objective and subjective aspects is not completely susceptible 
to the application of mathematics, both sets of thinkers are 
at fault. Philosophy, unlike physics, can still invoke the 
voluntarist theory of the universe. Freedom is no absurdity, 
because we know it in ourselves. Yet a Deus sive Natura who 
is essentially a Free Will is not satisfying to the logical mind, 
because such a theory threatens to dethrone reason. 

It may be that a new cosmology, such as is destined to 
bring the scientist and the philosopher more closely into 
agreement than ever before, is in process of formulation. That 
theology would gladly acquiese in such a scheme of thought 
which identifies the central principle of mind with a creative 
activity inspired by love is probable. For theology has never 
been rationalist in temper even when it has done its best to 
appear so. It can never be much more than an echo of 
practical religion, which has throughout its entire history 
been largely content to act first and justify its action after- 
wards. Its explicit creeds have had little more than a political 
significance; whereas its inarticulate faith has kept it true to 


a moral direction which is approximately uniform, accord- 
ing to the testimony of the universal history of Man. 

At this point it becomes clearer how anthropology may 
help mankind to a truer and better world-idea, or world- 
intuition. If the history of mankind shows that it has been 
orthoscopic, or rightly aiming, in the pursuit of good, then 
there is some point in life. But does history show anything 
of the kind? Can any history give unprejudiced evidence? 
This is perhaps where it is of advantage for an enquiry to be 
associated with the natural sciences, which have had little 
temptation to distort their facts as compared, say, with 
political or religious history. For the anthropologist, who is 
just one kind of historian among the rest, calls himself 
a man of science, and by so doing undertakes to write 
the most unbiassed and objective history that human 
nature can produce. Thus, firstly, as regards uncivilized man, 
on whose affairs his authority is not disputed, whereas his 
references to civilization are resented, he is careful to repre- 
sent the savage neither as a beast nor as a god, as did philo- 
sophers in the pre-anthropological age when disputing 
whether the state of Nature was one of war or of peace. 
Secondly, he tries to avoid any a priori identification of 
organic evolution with betterment. For him the word im- 
plies no more than the process of becoming more complex; 
and it is no part of his evolutionary presupposition that man 
has done well to abandon the simple life. This is a question 
of value, not of fact. 

Yet if it be asked whether the course of human life has 
been an emergence or ascent due to an immanent will to live 
well, it is obvious that the wide survey of the historical 
evidence which anthropology offers is bound to be exceed- 
ingly helpful. Anthropology is a science, not a philosophy, 
of Man. Indeed, anthropologists of the present day are in 
close agreement concerning the limits of their special task. 
Working on the very mixed material provided by somatology, 
technology, linguistics, and the study of institutions, they try 
to make these studies converge on ethnological problems 
namely, questions concerning the historical formation, dis- 


tribution, and survival of ethnic groups or peoples. It will be 
noted that they are prepared to explain how, if not precisely 
why, some types of human society survive while others 

Hereupon a philosophy of human history is needed such 
as will submit the bare facts of the time-process to analysis in 
the hope of discovering some normal relation between merit 
and destiny. The exceptional cases must be explained or, 
better, shown to afford indirect proof of the rule. The thinker 
who undertakes to justify the workings of the Good Will 
immanent in humanity by reference to the entire human 
record must be ready to become absorbed in the concrete. 
The ideological philosopher who speculates with definitions 
of the Summum Bonum will not be of use. But if one whose 
mind has received a thorough training in philosophy, and 
acquired the synthetic grasp which such an education can 
alone confer, will take the trouble to acquaint himself with 
the detailed findings of the anthropologists, he may be able 
to prove whether the biological evolution of man has also 
been accompanied by a moral evolution. 

An instance of the kind of work wanted is to be found in 
that admirable treatise Morals in Evolution, by the late Pro- 
fessor L. T. Hobhouse, which reveals a patient and critical 
scrutiny of the anthropological data, and yet exceeds anthro- 
pology in its attempt to establish a general law of human 
progress. As compared with the best work of the pure anthro- 
pologist such a philosophical interpretation of human history 
may, perhaps, never attain the same pitch of objectivity. 
Philosophy is to science as poetry to prose, putting a severer 
strain on the constructive imagination and consequently em- 
bodying more of the personality of the author. It is thus by 
no means certain that another who endeavoured to deal with 
the same facts in the same synoptic way would reach the 
some results. 

If one interprets Man's career through the ages as on the 
whole making for good, it is largely because of his own faith. 
He, too, is man, with no reason to suppose himself untypical. 
An affirmation supported by introspection must be the funda- 


men turn ret. We go to history in order to confirm our hopes, 
and even if it tells us that the world is against us we may 
decide to hope and act in defiance of the world's experience, 
which is not final and can be altered. Yet on the whole 
history is a sound critic of human endeavour. By its aid we 
can test our most cherished beliefs; and, if they seem in the 
light of the past to be false, it would be prudent to modify 
them accordingly. 

In the rest of this paper one whose studies have been 
divided equally between anthropology and philosophy will 
attempt a brief estimate of the moral value of the evolution 
exhibited by primitive society. He trusts as an anthropolo- 
gist that his facts are correct, but would have it noted that he 
is deliberately overstepping the borders of the anthropological 
field when he ventures to moralize on the meaning of the 
facts of history. 

Man has often been termed the rational animal. Of what 
avail would that be if he were not also the moral animal? 
Here, then, the question for us will be, How far is the savage 
a moral being, and one who is gradually advancing in his 
type of morality? The higher the type, let us assume, the 
more self-conscious in a word, the more ethical it will have 
become. Away with the pessimistic notion that final blessed- 
ness consists in getting rid of consciousness that the apothe- 
osis of mind is a mindlessness. Mental energy behaves in the 
very opposite way to physical energy, which, according to the 
modern theory, is subject to an inherent degradation. Mind 
pushes upwards from plane to plane, gaining power and 
radiancy as it develops. The moral quality of conduct de- 
pends on the motive. Using motive in a rather broad sense to 
cover purposive disposition, even when it fades back into 
mere organic adaptation, we can construct a rough scale of 
the evolution of motive having three grades unconscious, 
subconscious, and conscious. The first corresponds to the 
stage of animal instinct and need not occupy us here. By the 
time Man appears over the utmost edge of history he has 
already left the other animals a long way behind. Neander- 
thal man, for instance, to whom we are unwilling to concede 


the title of Homo sapiens, nevertheless could chip a flint to a 
handy and beautiful shape, could light a fire, and buried his 
dead as if there was a future life in store for them. The 
second and third stages have an important bearing on the 
present discussion, since they stand respectively for those pre- 
ethical and ethical conditions which, morally speaking, con- 
stitute savagery and civilization. Subconscious morality is 
half-willed. A man's acts are truly willed only when he con- 
sciously selects his ends, and does it self-consciously, so that 
he establishes a kingdom of ends, as Kant would say, for the 
benefit of the self. 

Our immediate object being simply to gauge the moral 
value of the uncivilized or primitive mode of human life, we 
can dismiss the subject of high-level or ethical living except 
so far as it supplies us with a standard whereby to judge the 
efforts of the savage to transcend his normal state of mind. 
This is always dim and groping. Its processes are uncritical. 
For the primitive man accepts his judgments about right and 
wrong at their face value. He can scarcely be said to make 
them, since he takes them as they come. Just as a child 
babbles in the words that his elders put into his mouth, so 
does the member of a primitive community follow the moral 
tradition of his folk without the slightest wish to change it 
for the better. Andrew Lang once composed the tale of Why- 
Why, the First Radical, to show how in palaeolithic times a 
man of Lang's own tastes and upbringing might have per- 
ceived in respect to Stone-Age humanity that " manners they 
had none and their customs were beastly." The only portion 
of the story that has even a symbolic bearing on history is 
the conclusion, which relates how Why- Why was very 
promptly done to death by his fellows. The non-conformist 
or the conscientious objector is quite unknown among 
savages; and it is fair to say that savages remain such for this 
very reason. Hence, anyone who contemplates a primitive 
society from a certain distance has the illusion that it is 
stationary, just as if he were watching a so-called fixed star. 
For the last few centuries civilized society has been moving 
so fast that by contrast the old-world rate of progress seems 


no advance at all. The further back one looks, the more in- 
credibly slow is the pace. During the Ice Age the very glaciers 
went faster than man, and yet the comparison of one millen- 
nium with the next will always reveal a certain cultural 

The humblest savage has a culture of some sort, whereas 
no other animal has. Man has a social inheritance in the 
shape of a hoard of properties and precepts which accumu- 
late, as it were, by themselves, whereas animals have only 
individual experience, including a little early training. Often 
a savage sees a good thing right under his nose and throws it 
away because he shies from the new thing. If some genius, 
bolder than the rest, exploits it for his own purposes with 
success, little intelligence on the part of the others is needed 
to copy his example. Thus fashion is the basic law of primi- 
tive culture. Moreover, fashions change, though nobody at 
the time is more than half aware of the fact. If they change, 
it will usually be for better or worse. Now a society strong in 
other ways can doubtless indulge in some bad habits without 
suffering greatly. Primitive folk exist on a very small margin 
of safety, so that a pernicious fashion soon weeds them out. 
Either Nature exterminates them or they succumb to some 
other enemy; the latter fate being preferable, since at the 
hands of such a taskmaster they may learn to change their 
habits before it is too late. Indeed, the more radical changes 
of custom observable in the primitive world seem mostly due 
to external contacts, and these for the most part were not 
gentle. Moral progress by means of self-education has hardly 
begun. An ethical morality is dynamic, whereas a pre-ethical 
or customary morality is inferior to it because it is inert. 

Yet there are compensations. The higher morality is 
more experimental, and consequently exhibits a clashing of 
standards which is disturbing to those, always a majority, 
who need a bell-wether to lead their steps. These hesitate and 
are lost, so that under civilized conditions many are morally 
in a worse case than they would be if they lived in a primi- 
tive community. For in the latter everyone knows his station 
and its duties, and everyone is therefore disposed to play the 


part expected of him. It would shock himself as much as the 
rest if he were to act unconventionally. Though morality 
always costs an effort, it needs less of that willed effort which 
feels like movement in the line of greatest resistance if one 
suffers merely in order to be respectable. Thus it is that to 
many who have lived in the midst of it as, for instance, the 
naturalist, A. R. Wallace savage society seems miraculously 
well-behaved. So it is, but in a passive and negative way, 
inasmuch as it is obsessed by a traditional set of habits which 
dominate it, the bad with the good. A man does the right 
thing for a positive reason, but the correct thing merely be- 
cause it never strikes him that anybody could act otherwise. 
So far it has been necessary to insist on the difference 
between savage and civilized morality taken each at its 
normal best. It is the part of every sound anthropologist to 
recognize it as a real difference in the social and mental level. 
Thus he can assure the administrator, on the one hand, that 
primitive folk may be trusted to be decent according to their 
own lights if left to manage for themselves. On the other 
hand, he must allow to the educator that, before they can 
acquire the spiritual freedom that goes with moral individu- 
ality, a long and careful training is required such as will 
develop their intelligence in all directions. This difference, 
then, exists, but it is not a hiatus, since it can be bridged. To 
make this latter point clear let us seek within savagery for 
the promise of a morality of the reflective type. It may well 
be that, when we look a little more closely into the regime of 
custom, its lack of conscious motive may wear another aspect. 
We may have to agree on the strength of the evidence that 
it is possible within certain narrow limits to be inarticulately 
conscious of certain ends that directly and obviously con- 
dition the good life. The real trouble caused by such in- 
ability to translate feelings into communicable thoughts may 
be not so much that it interferes with the intenslveness as 
with the extensiveness of the resulting morality. Conscious- 
ness of kin may be a duty that almost goes without saying, 
but consciousness of kind cannot develop out of it until it has 
been preached in plain language up and down the world. 


Darwin somewhat quaintly observes in The Descent of Man : 
" The very idea of humanity, as far as I could observe, was 
new to most of the Guachos of the Pampas." No doubt it 
was. One wonders indeed in what possible terms the great 
naturalist could have presented the notion to such simple 
folk. But it by no means follows that the Guacho did not 
have dim feelings of humanity towards his own people, or 
even a dim feeling that he ought to have such feelings. 

One may begin by trying to picture the simplest Kind of 
domestic group known to the anthropologist. Though in the 
genetic sense the family must always consist of father, 
mother, and children, it by no means follows that this 
relationship should necessarily involve any permanent asso- 
ciation on the part of the parents. On the contrary, effec- 
tive symbiosis may in general have taken quite another line, 
as certainly happens in those frequent cases when the woman 
remains with her brethren, and the father of her children 
merely visits her temporarily, and it may even be furtively, 
from that other fireside when he usually squats and sleeps 
surrounded by his sisters and their progeny. Such extreme 
mother-right gives rise to a uni-parental family which without 
change of form enlarges into the matrilineal clan. Whether 
this is universally prior to the patrilineal clan is still an open 
question, but there can be little doubt that, typologically at 
all events, it is the more rudimentary type of organization. 

The moral relations within such a narrow group, except for 
its somewhat casual amours, may be regarded as socially self- 
sufficient. Three major injunctions, two negative and one 
positive, form the nucleus of its moral code. There must be 
no incest, and no intestine murder, and the death of a kins- 
man must be avenged. What sanction, in the next place, 
lends to these laws that stringency which all the known facts 
show to be as nearly absolute as human laws can possess? 
Some theorists would account for it all in terms of instinct. 
But instinct is more or less automatic in its effect, whereas the 
very imperativeness of these ancient prescriptions shows that 
they stand in constant need of being enforced. The sanction 
is so much a matter of consciousness that it has a character at 


once nascently legal and nascently religious. Thus, on the 
one hand, offenders are relentlessly punished by death or 
by excommunication. On the other hand, a belief in the 
sacredness of the common blood the blood of the mothers 
turns such offences into sins which, if they went unpunished, 
would bring universal ill-luck and ruin in their train. 

For the little group concerned these commandments are 
quite explicit. They may even have explicit grounds, in so 
far as the thought of their violation provokes a sense of public 
injury and vague fears of misfortune. Among folk so closely 
huddled together it would be obvious that murderous quarrels 
about their own women or about anything else would render 
comfortable intercourse impossible; while, again, they could 
hardly weep together over their slain without fiercely clamour- 
ing to be revenged on the slayer. Yet one cannot argue that 
such group-life explained itself without the co-operation of 
the mind. The three laws in question are artificial creations 
of the human intelligence. Based on a one-sided notion of the 
family that ignored the father, they worked queerly from the 
first, and involved contradictory dispositions such as those 
severally needed for making courtships and vendettas with 
the next group. Considerable readjustment had to be made 
in their foreign policy before the various clans could coalesce 
into some sort of tribal union; and such a process, with all the 
mixing and discussion, must have wonderfully clarified their 
conceptions of what they wanted and of how it might best be 
obtained. We learn, for instance, from Spencer and Gillen 
that the Central Australians during some festal gathering of 
the usually scattered groups would hold informal councils at 
which the elders discussed matters touching the common 
welfare. Thereupon not only did they decide on executive 
details, but would likewise act freely in a legislative capacity, 
modifying even such fundamental principles as those of the 
marriage law. It is to be noted that the primitive conservative 
saved his face on these occasions by voting for a sort of pro- 
gress backwards, the stock argument for a reform being that 
they must return to the customs of their ancestors of the 
Golden Age. 


If further proof is wanted that moral law is not merely an 
echo of blind animal propensions, but stimulates the creative- 
ness of man which to succeed must also risk failure in its 
vital experiments, we may consider the revolution in senti- 
ment that takes place when mother-right gives way, as would 
seem to be the inevitable result of social evolution, to father- 
right of some kind. It is true that sometimes the new system 
is bi-parental, the mother's people never entirely relaxing 
their hold on the newly constituted family, which to a corre- 
sponding extent becomes a partnership, as when the children 
inherit the earnings of both parents or, more rarely and by a 
later development, are allowed to share in kin-property be- 
longing to either side alike. Often, however, father-right is as 
lop-sided in its attitude towards conjugal equality as the more 
primitive system that knew no other symbol of social union 
except the mother's blood. Nor is this extreme type of 
patriarchalism confined to savages, for even civilized peoples 
such as the ancient Romans or modern Chinese have based 
their ethics and religion upon it. From a moral point of view 
the extraordinary interest of this radical change in the consti- 
tution of the family consists in the complete transference of 
the obligations of kin from one parent's group to the other's. 
To speak of the husband as a parent in this connection is 
perhaps to antedate the actual progress of human thought 
about the mystery of procreation. In Australia and New 
Guinea there are patrilineal peoples whose theory of genetics 
entirely overlooks the function of the male. The man, or 
rather his group, is owner of the woman and her offspring; 
yet of these she is still the sole vital source, apart from the 
supposed co-operation of certain reincarnating ancestral 
spirits. She would therefore still have every right to rank as 
high-priestess of the sacred blood, had not the religion of the 
blood-tie been in the meantime transformed. One can hardly 
suppose that some new metaphysic of transmigration was 
potent in itself to effect so mighty a change. Social con- 
venience must be invoked to account for it. From this 
moment onwards the duties of respecting and protecting the 
blood were transferred, with a complete alteration of mean- 


ing, to the kinsmen of the father. These in theory contributed 
no blood, but in fact transmitted the local name, with all the 
spiritual implications it might have as, for instance, if it 
were totemic. Henceforth as before a man must marry out 
of his group, respect life within it, and be vengeful on its 
account; and yet he must now forget the mother's blood that 
was in him in order to respond to the mere magic of a name. 
Only metaphorically could he any longer claim to be " all 
one flesh " with his brethren, or at most could simulate a real 
blood-brotherhood by some rite of actual transfusion. In 
substance the meaning of the blood was gone. Nevertheless, 
through the shadow that is, by means of the symbolism of 
the name enough of the old force was transmitted to the 
new order to give it such a legal and moral sanction as would 
secure its stability. In place of a fact for maternity is a fact, 
whereas paternity is an inference a fiction must suffice as 
the formal basis of social fellowship. Here, then, as more 
than ever before was the opportunity of consciousness. So 
great a paradox called for some hard thinking. A sense-sym- 
bolism, almost a matter of sight and taste and smell, had been 
replaced by a word-symbolism such as is the chosen medium 
of all articulate thought. 

A loose aggregation of inter-marrying clans kept apart by 
feuds, unless momentarily drawn together for common war- 
fare or perhaps for the performance of religious ceremonies 
entailing a " truce of God," gradually knitted itself into closer 
confederation. North America, as contrasted with Australia, 
furnishes many examples of such a consolidated group- 
system, of which the best known is perhaps the famous Iro- 
quois League of the Five Nations. At this point, at which 
more or less mobile bands of hunting folk are replaced by 
agricultural settlements densely massed together, the form 
of society changes. Wealth and war between them are now 
responsible for the appearance of aristocracy and a class- 
system. Correspondingly, there is more need than ever for 
intelligent government if the state is to be held together. 
This is the beginning of the Heroic Age, where the man of 
outstanding individuality, king or priest or the two in one has 


a chance of reorganizing human life on a considerable scale 
and in the light of his own constructive ideas. This is the 
transition to barbarism and the dawn of civilization. 

The progress may be studied from the inside by attending 
to the accompanying development of religion. The psycho- 
logy of primitive man is revealed more clearly in his religion 
than in any other activity through which he can give expres- 
sion to his intimate feelings and thoughts. No doubt one 
could with some difficulty distinguish a secular side to his 
festivity, fine art, literature, science, and philosophy; but such 
rudiments as would remain after they had been parted from 
whatever was of religious origin and import would scarcely 
be worth notice. 

There are anthropological authorities of great distinction 
who disbelieve in this alliance. Sir Edward Tylor has declared 
that the connection between morality and religion is second- 
ary and late. This is so hard to believe that one is tempted to 
treat the difficulty as one of words only; for some would 
prefer to strain the term " magic " so as to cover sacred rites 
not overtly addressed to a god rather than to give the word 
" religion " so broad a connotation. Otherwise, how deny the 
very early and truly primal relation of moral law to tabu? 
Yet tabu invariably has, if not a god, at any rate the unseen 
powers at its back. Human personality must presumably 
have developed in a corresponding degree before such deifi- 
cation can take place. Even backward folk such as the Aus- 
tralians can imagine a sort of Arch-mage, a magnified leader 
of the ceremonies, who presides over the initiation of the 
young men. It is he who imparts to them those manly virtues 
which the rites in their entirety, as their expressive symbol- 
ism shows, are designed to bring forth by a process of spiritual 
rebirth. It seems needless hair-splitting to concede that these 
savages have religion, and yet to deny it of other Australians 
who hold similar initiation ceremonies except for the fact 
that the regeneration is held to be effected without the aid 
of a god. Yet unless one either depreciates the claim of 
Daramulun of the Yuin to be what Andrew Lang would call 
"the high god of a low race," or else supplies the Arunta 


with such a Supreme Being as the one for whom Sir Baldwin 
Spencer searched and, to check the contrary statement of a 
German missionary, searched again in vain, we are faced with 
the absurdity that what Sir James Fraser distinguishes as 
"the age of religion" and "the age of magic" are found 
together not only at the same moment, but at the same level 
of morality and general culture. While the theorists are de- 
ciding about a terminology, let us make religion something 
common to mankind. 

Human religion regarded through the ages exhibits two 
tendencies which can be taken as constant : it feels deeply, 
and it thinks and speaks darkly. These are two sides of one 
fact, in that some intimation of the whole in the shape of a 
prophetic feeling must precondition any attempt to master 
its content bit by bit. Not only is this good logic, but history 
bears it out by showing that our race has always seen beyond 
the present. One can recognize the future lord of creation, 
for instance, in the totemite who without the slightest know- 
ledge of how to domesticate animals or plants already im- 
agines ways of controlling their multiplication. Something in 
him tells him that it can be done, and, though he fails at first, 
he tries again until he does it. Instead of passively acqui- 
escing in the actual, as on the whole the mere animal might be 
said to do, Man with his high brain is always more inclined 
to treat it as the potential to pretend, as it were, that it is 
more than it is. Religion does the same thing on the grandest 
scale, uniting all our minor efforts to elicit the promise from 
our surroundings. It refuses to take the world as it finds it, 
but reads into it a sort of infinite plus. M. Levy-Bruhl has 
described the essential savage as a mystic, and the opposite 
of a mystic is apparently a positivist. It is highly doubtful, 
however, if there is a true positivist belonging to the human 
species; for the type is subhuman. There never was a more 
ardent mystic than the physicist who explores immensities 
ranging from the galactic system to the electrons constituting 
the atom. But a man's own mind-stuff is even more in- 
triguing. To get more out of oneself is the ultimate purpose 
of the serious life. Hence religion, though it has always main- 



tained a certain cosmological interest, is primarily concerned 
with the soul; for what we put into things is what we have 
first to get out of ourselves. Moral and spiritual evolution 
comes by willing the existence of the better intelligently and 
therefore freely, inasmuch as freedom is the preperception of 

The savage's religion is essentially a self -stimulation, a 
means of stirring up the feelings to that pitch at which they 
fluctuate between extreme exaltation and extreme depression. 
He realizes that such transports act as a spiritual purge. Not 
only does the relatively civilized Ashanti defend occasional 
saturnalia as a method of rendering the heart " cool," but the 
rude black fellow of Australia, when he engages in one of 
those queer judicial duels at which the parties crack each 
others 5 crowns with alternate blows of a club, explains to the 
protesting white man "that always done, then angry no 

This process of Man's biological history shows the human 
species to have avoided the specialization of functions that 
goes with fixed instincts, and consequently to have remained 
nervous and highly strung, because he is liable at decisive 
moments to be undecided about them. We need not think 
of the early savage as merely starting at shadows, though un- 
doubtedly he did this, and it helped him to become an 
animist. The world contained plenty of unpleasantly real 
things. Primitive man improved his powers of attention by 
being naturally excited and then by making himself volun- 
tarily more excited. 

To the savage everything of outstanding interest, whether 
it be wonderfully useful, or wonderfully dangerous, or simply 
wonderfully perplexing, is both mana and tabu, but, pri- 
marily and positively, mana. It is "wonder-working" for 
good or evil; and that is why it is tabu, " not to be approached 
lightly." This wonder-working power is to be controlled by 
religion for the benefit of man, so that the good or divine kind 
may be separated out and preserved, while the bad or devilish 
kind is purged away and destroyed, Savage religion has this 
aim, and it proceeds to reach it by displaying what might 


seem to the unthinking observer an unnecessary excitement 
over every event of any importance in the social or individual 
life. It exaggerates this importance, as it were, by treating 
the occurrence as if it were veritably a life-or-death affair. 
Good being everything that helps life, and bad being what- 
ever leads to death, religion gives this tremendous significance 
to all such hopeful or fearful anticipations as may be awaked 
by any experience out of the common. Good without end 
and evil without end are always the ultimate implications of 
lucky and unlucky; and, to state the matter in its barest 
terms, these categories are fundamental for primitive religion. 
From fetish or totem to High God, all are, on a minimum 
definition of their function, so many means of securing luck. 
If, however, we substitute life for luck, we are nearer to their 
true meaning. 

The emotional side of the savage cult of the sacred easily 
slips into extravagance because of its inability to distinguish 
the sacred from the unclean, the supernormal from the ab- 
normal. The man who is in contact with mana hardly knows 
whether he is possessed by god or by devil, whether he is 
inspired or merely intoxicated. As far as the mere feeling 
goes it would seem that both conditions appear very much 
alike to the subject, so that some other criterion is required if 
the profitable kind of experience is to be distinguished from 
the other. Whether we call it sense, intuition, or reason, a 
faculty of judgment must be invoked. The difficulty is that 
the religious man is always standing on the very threshold of 
the unknown. All certain knowledge such as he may seem to 
have is behind him, and he is reaching forward to that which, 
being uncertain, is fraught with inevitable risk. Religion is 
experimental because life itself is so. 

To proceed to an assessment of the intellectual factor in 
primitive religion, it has already been noted that religion 
always speaks and thinks darkly that is, symbolically. Its 
reach must exceed its grasp. Now advanced religion, by 
means of a word-symbolism full of abstract terms, can con- 
struct a language of hope rich in suggestions of desirable 
things in excess of all human measures. The savage, on the 


other hand, has a poor vocabulary and trusts mainly to con- 
crete things for his images. One must not forget, when one 
sees a jumble of his crude emblems in the show-cases of some 
museum, that in their proper ceremonial setting they were 
the vehicles of faiths and aspirations none the less intense for 
being otherwise almost mute. Even if such material symbols 
were absent, the movements of the performers of some mimic 
dance are a kind of gesture-language. Yet words, though few, 
count enormously. Early gods are hardly more than names of 

Primitive religion is subconscious, lacking in theology, and 
knowing itself almost entirely through its actions, together 
with the feelings aroused thereby. These Actions are as many 
and various as those embraced in the social life. Every custom 
is a rite inasmuch as it is part of a sacred tradition. Religion 
becomes aware of its aims more especially in operations of a 
purely ceremonial character, in which the transcendental 
nature of the blessing sought is obvious. At the lowest level 
of cult, which from a doctrinal standpoint seems almost god- 
less, it is hard to extract from the participants any clearer 
notion of their object than that somehow their hearts are 
made stronger. It is quite a mistake to suppose that they have 
material benefits in view and these only. They have found 
admission into an inner world which is in control of the 
outer. They may not yet have thought out the prepotency of 
the spiritual, but at least they have danced it out. 

In this discussion the history of primitive mankind has been 
surveyed under the heads of social organization and religion. 
This is in accordance with the usual practice of anthropolo- 
gists, and offers a method that can be made sufficiently com- 
prehensive for our purpose, which is to consider human 
history as a moral evolution. Under the head of social organ- 
ization can be grouped such subjects as economics, politics 
and law, and all that has to do with the material interests of 
mankind. Under the remaining head of religion falls in turn 
all that concerns our spiritual interests. Fine art and litera- 
ture, science and philosophy belong to this division. Some 
might indeed think that science, which has provided so many 


useful mechanical inventions, is on the side of the material 
interests; but this is a complete misunderstanding of its true 
aim, which is speculative. Greek mathematics and physics, 
for instance, were not the by-products of a utilitarian outlook 
on life, but were pure recreations of the mind. Indeed, these 
spiritual activities here classified under the general notion of 
religion may be termed recreative in their function, as con- 
trasted with the material class, which may be distinguished 
as preservative. One must live before one can live well. 

We alone of animals have culture and appear to owe it to 
religion as mother of the recreative arts which seek the wel- 
fare of the soul, while the preservative arts are merely pro- 
viding the security of the body. One could almost speak of a 
lower deck and an upper deck morality, the one concerned 
with handling the vessel, the other with laying its course by 
the stars. Social organization develops plenty of common 
sense. But common sense does not try to see far ahead, being 
urged on from behind. Religion, on the other hand, ought to 
be thinking ahead all the time, since its business is to use a 
telescope as well as night and fog will allow. It must forfeit 
its place at the head of the recreative disciplines only if it 
were to forget to face the unknown, and instead look back 
over its shoulder to church history, which concerns the 
temporal rather than the spiritual side of life. The savage's 
religion is his University, the forcing-house of his higher 
culture, the seed-bed of his soul. No one can study the facts 
of his moral evolution without taking note of this. The pure 
anthropologist is primarily concerned with origins, and so 
considers this process mainly from what, in point of time, is 
the hither end. In our philosophizing on Man we have re- 
garded it from the far end teleologically. Viewing it in this 
way, as a pursuit of good, growing ever more conscious, 
though never perfectly so, can one say that a steady gain in 
good has come of human evolution? The answer seems to 
be, Yes. 


By J. B. LEATHES, M.A., F.R.S. 

Sometime Professor of Physiology in the University of Sheffield 

IN the trivial intercourse of daily life there are two sub- 
jects of conversation commoner than all others, weather 
and health. In the history of the growth of human know- 
ledge also these two subjects have been from the beginning 
the principal incentives to enquiry. The dawn of physical 
science came with the observation and recording of times 
and seasons and their relations to the heavenly bodies. 
Astronomy and Mathematics came into existence in this 
way in days before the earliest records of history. By the 
habit of observation so formed, together with the invention 
of new methods for measuring, recording, collating and 
reasoning from the facts observed, men were led to the study 
of the laws of motion, of heat and light, of the nature and 
constitution of the atmosphere, of storms, tides, humidity 
and drought, electricity and magnetism. All that body of 
knowledge that has come to be included under the term 
physics can be traced back to a common origin in the ancient 
interest in the weather. The ancient interest in bodily health 
has been no less important. From the earliest times the wise 
concerning health rivalled in popular esteem those who con- 
structed the first calendars, and from their endeavours there 
came forth in due course no less notable a progeny of 
sciences; chemistry, botany, zoology. To this day the art 
and practice of medicine grows and is nurtured by the 
scientific study of the human body. The science of physi- 
ology, which has grown out of this study, has always been 
the handmaid, or rather the foster-mother, of medicine. 

But in spite of its origin in what so nearly concerns every- 
one, physiology can never be a popular science. Its relation 



to medicine makes men fear the danger of a little knowledge. 
In popular astronomy there is no such danger. If astronomy 
can be a popular science and physiology cannot, it is not be- 
cause the mental equipment necessary for understanding its 
achievements is nearer that of the average man. Everyone 
who is not an astronomer must stand in awe of the achieve- 
ments of astronomy, and the more so the more deeply he 
has studied other branches of science. The seed from which 
physiology sprang may have been sown as long ago, but it 
was slow to germinate and hard to cultivate. It did not be- 
come fruitful until about 300 years ago. When astronomy 
germinated no one knows, but it has borne fruit for perhaps 
as many centuries as physiology has years. That does not 
mean that we today have become familiar with its methods 
of calculation, and the intricacy of the tackle that it uses, or 
even that we have any intimate knowledge of the precise 
problems with which it is engaged. Of all this the public is 
as ignorant as it is of the common occupations of the physi- 
ological laboratory. But from the earliest ages down to last 
week astronomy has set and kept men thinking upon the 
history of the world above and beyond the earth on which 
they live : and these regions are a favourite field for the 
imagination of every reflecting person. 

Physiology, too, has spread its borders far beyond the study 
with which it began. There has been no choice in the matter. 
It is true that nearly all who have worked in physiology, if 
they have not actually practised medicine, set out in the first 
instance with that intention. Many of the activities of the 
human body, the working of which they had to get to under- 
stand, are so closely similar to those of simpler animals, 
some essentially the same as those of plants, that the oppor- 
tunity and the hope of investigating them with success is far 
greater if these simpler types are studied in comparison with 
the processes of life in man. Much that is relevant and of 
value in the physiology of man has been learnt from the 
study of organisms as far removed as the yeast plant, and 
enquiry, the ultimate motive of which can be traced back 
to the needs of the physician, will not rest until all has been 


learnt that can be learnt of the activities by which all forms 
of life maintain their living existence. 

Direct experimentation on man is rarely possible. When 
it is it is usually based on knowledge previously gained from 
the experimental study of other species, in which similar 
problems present themselves uncomplicated by influences 
which confuse the picture in man. Without such experi- 
ments little progress could have been made. The advance 
of medicine is delayed by limiting investigations to its im- 
mediate needs. 

Physiology now embraces all those chapters of biology 
which deal with the contributions made by the different 
parts of an organism to the well-being of the whole, to the 
maintenance and fulfilment of its life : and since an organism 
may be a single cell and every organism starts life as a single 
cell, the study of the contributions that the parts and com- 
ponents of a cell make to its well-being is logically the 
starting point of physiology. The largest animal cells rarely 
exceed a diameter of 1/250$! of an inch, and the average 
dimension is less than a tenth of that. The study of the parts 
of which they are composed, the anatomy of cells or cyt- 
ology, is therefore a microscopical science, and the physi- 
ology of the cell has also to be microscopical except where 
it is possible to study the properties and activities of large 
numbers of identical cells free from mixture with other 
varieties. But we cannot stop at the study of structures 
within the cell recognizable under the microscope. Ulti- 
mately the parts of which a cell is composed are the mole- 
cules of the various chemical substances found in it. The 
dimensions of the largest molecules are less than i/r,oooth 
of the dimensions of a small cell. Can we learn anything of 
the contribution to the fulfilment of the cell's life made by 
any of the kinds of molecules found in it? 

The materials of which living cells, both animal and 
vegetable, are composed can be resolved completely into ele- 
ments that are among the commonest of those that occur in 
matter which exhibits none of the phenomena of life. But 
in the substances obtained from cells the atoms of these ele- 


ments are arranged in molecular configurations of extreme 
complexity. Is it the peculiar complexity of these arrange- 
ments of atoms that confers on the common elements the 
powers exhibited in living cells, which are composed entirely 
of these elements? If so, physiology ultimately resolves itself 
into a special form of chemistry, for chemistry is the science 
which defines the ways in which atoms of the elements 
arrange themselves and the properties exhibited by each 

Perishability is one of the properties of the material of 
which a living cell is composed. Not only must a cell ulti- 
mately die, it is continually perishing as long as it remains 
alive, but the loss of substance which it thus suffers it as con- 
tinually makes good by the assimilation of foreign material, 
food, which it transforms into material similar to that which 
perishes. As fast as the substance of the living cell decays it 
is renewed; or even faster; for it may grow. Growth, how- 
ever, is only an incident in the life of a cell or of an organism; 
the cell or organism does not cease to live when it ceases to 
grow, it merely strikes a balance between the rate at which 
new living material is formed and that at which the old 
breaks down. This assimilative transformation of unor- 
ganized matter by the substance of the cell is a phenomenon 
inseparable from life and nothing like it can be observed 
otherwise in nature: it is one of the riddles of biology. Is 
this power a property conferred on the cell by the peculiar 
constitution of the chemical substances of which it is com- 
posed? If it is, the ultimate fundamental problem of physi- 
ology is to find out all that can be known of the configura- 
tions and arrangements of material elements in which it 
resides. Sooner or later these arrangements are dissolved and 
the elements taking part in them turn to dust again. How is 
it that the frail, perishable dispositions of the elements of 
dust are during life daily renewed and maintained? Chemi- 
cal investigation of the composition of cells has revealed sub- 
stances of an almost infinite complexity and variety that only 
living cells can make; in the constitution of many of these 
substances it has made clear certain chemically definable 


features, and in the case of others has also made clear certain 
powers that reside in them by which the chemical behaviour 
of adjacent foreign material can be altered. These powers 
are known to have great influence on the course of chemical 
events peculiar to living cells and to contribute to the fulfil- 
ment of the life of the cells. But this throws no light upon 
the way in which what is simple and lifeless is assimilated 
by what is alive and then is endowed with life. By the time 
the substances which can be obtained from living cells can 
be analysed life is gone from them, and even when the 
baffling perplexity of their nature has been clarified, what 
they were when they shared in and contributed to the life 
of the cell and why they were different then may be as 
obscure as ever. No one can say how much, if any, light 
even complete clarity as to all details in the chemical con- 
stitution of proteins and the other mysterious components 
of cells will throw upon the processes by which the living 
material builds itself up anew from the simpler materials 
which are its food, and continues to do so so long as it lives 
and when it ceases dies. It may not be logical to expect that 
what can live should reveal its nature through analysis of 
what is dead. But none the less everything that can be learnt 
of the nature of the material that has served it is relevant for 
the study of its powers. Physiology has waited on anatomy 
from the beginning. It waits now in hopeful but uncertain 
expectancy upon the chemical anatomy of the cell. 

This implies two things. First, the chemical configuration 
and internal structure of the molecules which only living 
cells can produce and of which, by the time any analysis is 
possible, they appear to consist; and secondly, far more diffi- 
cult even than this, the way in which the different kinds of 
molecules link up to form the internal fabric of the cell. 

Physiology as usually taught and studied is mainly con- 
cerned with higher animals. All the parts of which the body 
of a man or other animal is composed are themselves com- 
posed of cells or of material investing cells that has been 
deposited by them; and all the cells have been formed 
originally from a single egg-cell. The egg-cell as it grows 


divides into two, each half again into two, and so on, till in 
the fully grown man there are many billions of cells. In his 
blood alone, of which he has about 5 litres, each litre con- 
tains 5 billion red blood corpuscles (5 x io 12 ). The first cells 
formed by the division of the egg-cell are alike, but as divi- 
sion proceeds differences begin to appear in different parts of 
the cluster of cells and the differences become more and 
more pronounced. The different parts acquire peculiarities 
of structure and of grouping that enable them to serve the 
rest of the cluster in different ways so that the cluster be- 
comes an organism composed of different organs. 

A single cell may be a self-sufficient organism; it is then 
so constituted that it can provide for its needs by taking 
up food and oxygen directly from, and discharging waste 
directly into, the water with which it is in contact. In so do- 
ing it avails itself of the violent commotion, kinetic activity, 
of molecules or ions dissolved in the liquid state or freely dis- 
persed through space in the gaseous state. It has no fellows 
to which it can relegate any of the duties. 

In a man's body every cell has the same common primitive 
needs : it must have food, as a fire must have fuel; as a fire, 
too, it must have oxygen and it must not be choked by the 
fumes and ashes of its own burning. But it is only a few of 
the cells in his body that have direct access to the food he 
eats. Even of those over which the food passes, in his mouth, 
throat, stomach, and intestines, it is only those in the in- 
testine that actually take it up directly. The cells lining the 
surface of the intestine do so and hand on what they them- 
selves do not use to the blood that streams in fine capillary 
tubes close by them. All other cells than these are entirely 
dependent on the blood for their supply of food. So, too, 
with the oxygen that every cell in the body must have; this, 
too, has to be conveyed by the blood, and it is only in the 
innermost parts of the lungs that the air is brought into 
sufficiently close relations with the blood for the oxygen to 
be taken up by it. If the air in the lungs is not constantly 
renewed by the movements of the chest, and the blood kept 
circulating through the capillaries of the lungs in the closest 


relation to this air, the fact that the body is surrounded by 
air containing oxygen is of no avail; the body is unable to 
get oxygen from it and in three minutes the man is dead. 
The removal of waste similarly can only be done by the cir- 
culating blood. Cells on the surfaces of the body may be in a 
position to shed some of their refuse where it can do no harm 
and be rubbed or washed away; but the vast majority of the 
cells in the body depend entirely upon the circulating blood 
for this primitive service. There are certain parts of the 
body where the blood can unload this refuse and purify 
itself; in the lungs it emits carbonic acid gas which can 
escape with the air expelled from the chest; in the kidneys 
substances dissolved in water can escape and to a very much 
less extent on the skin or the internal surface of the bowel. 
If a man's kidneys cease to act he dies in four or five days. 

For all these essential services rendered by the circulating 
blood all vertebrates depend upon a machinery that in its 
general plan is broadly the same. The blood flows in the 
finest capillary tubes, about i/3,oooth of an inch in bore, 
close past the cells that make use of it. It is supplied to these 
tubes under pressure by small arterioles, the walls of which 
contain muscle; this muscle, by its contraction or relaxation, 
controls the amount dispensed. The arterioles lead from a 
system of arteries, tubular branches of the great vessels fed 
by the heart itself, which form a distensible elastic reservoir 
filled with blood under pressure; much as the bag of a bag- 
pipes forms a reservoir of air under pressure that escapes 
through the drones or the keys of the chanter when the pipes 
are playing. The bag is kept filled by the piper's expiratory 
muscles; the arteries by the muscular walls of the pump-like 
valved ventricles of the heart. As long as there have been 
vertebrate animals on the earth this sort of machinery has 
been perfected and in general use, and even long before that 
many features of this system were in existence in inverte- 
brates. For millions of centuries this system has worked, and 
survived because it worked. How long it took to be sketched 
out before that cannot be guessed. 

Cells of many kinds are used in its construction; quickly 


acting muscle cells for the heart; for the arterioles more 
slowly acting muscle cells capable of remaining in action for 
hours at a time; cells that secrete a web of fibres investing 
the tubes in due measure according to the strains to which 
their walls are exposed from the pressure of blood within 
them; here fibres that lie slack around the undistended vessel 
take up the slack as the vessel distends but then hold fast 
and do not give, acting much as the net about an inflated 
balloon; there fibres of another kind, with no slack, that give 
under strain only to pull things back into place again by 
their elasticity as the strain passes; each kind of fibre appear- 
ing in due amount as required and where required, formed 
in response to the strains felt by the cells which secrete them, 
maintained so long as the strains persistently recur, wasting 
and disappearing when they cease; cells again of a totally 
different kind, which line every part of the tubular system 
in which the blood flows, a smooth sheet of the thinnest tes- 
sellated cells which, appropriate in many other ways, have 
also mysterious properties by virtue of which the blood that 
clots so easily when it escapes remains fluid indefinitely when 
in contact only with them; these same cells in the capillaries, 
the only part of the vascular system in which the real busi- 
ness of the blood is transacted, forming the only retaining 
wall for the blood stream, a retaining wall not more than 
i/25,oooth of an inch thick, so thin that what all the other 
cells of the body need of the blood can pass through without 
let or hindrance and yet the corpuscles and even large pro- 
tein molecules be kept in their proper place within; in fact, 
everywhere in the circulatory system, as throughout the 
body, cells, all of one common parentage, which nevertheless 
in each part have those particular properties and powers 
which fit them for the work there in hand, properties and 
powers called into existence by the influences to which the 
cells are there exposed. It is not difficult even for one who 
has not studied the subject in detail to appreciate how far 
we are from understanding the adjustments of their chemi- 
cal anatomy involved. 

Moreover, the needs of different parts of the body are dif- 


ferent at different times. When a man is asleep his muscles 
are at rest. They will, therefore, not need oxygen or fuel in 
anything like the same quantity as when he is actively en- 
gaged in laborious occupations. His eyes are shut; when he 
is awake and they are in use they may evoke through other 
parts of the nervous system many different kinds and degrees 
of activity which are not evoked when he is asleep. For each 
kind and degree the machinery on which the amount of 
blood dispensed to each part of the body depends is adjusted 
so that the needs of the moment in each part are met by a 
corresponding supply of blood. As the need passes the supply 
is reduced again, with due regard to economizing the energy 
of the heart. In a given emergency a man may, without tak- 
ing thought, spring into action and do in the exactly ap- 
propriate way something that requires all the energy that he 
can command. He may put every ounce of his strength into 
what he does; but every ounce means in the account ren- 
dered so much more oxygen to be delivered by the blood, so 
much more energy expended at the cost of food to be brought 
by the blood, so much more carbonic acid gas produced to be 
carried by the blood to the lungs. It is clear that there must be 
much more for the blood to do in working muscles; we know, 
in fact, it may be a hundred times as much. It would be ex- 
travagant if the ordinary service supplied blood so freely that 
it covered even exceptional demands such as these. How is 
the maximum of efficiency to be combined with the maxi- 
mum economy? The muscles with which a man works his 
limbs consist of parallel contractile fibres. In a section across 
these fibres, each of which is a i/i,oooth of an inch or so in 
diameter, it may be seen under the microscope that each 
fibre has running parallel with it, and therefore also cut 
across, a number of capillary bloodvessels, visible as dots at 
two, three or more points on its circumference. To make 
them visible a little indian ink can be injected into the circu- 
lation of an anaesthetized animal before death. Any blood- 
vessel containing blood will then appear as a dark spo^. If 
the muscle examined was at rest capillaries will show up 
only here and there as dark specks; for most of the muscle 


fibres none may be in evidence. If the muscle was in action 
immediately before the animal's death ten, twenty, or fifty 
times as many capillaries may be seen and most of them 
much more fully distended with blood. The capillaries in 
certain parts of a living frog can be watched under the micro- 
scope and the blood seen flowing through them. They can 
be seen to open for a time and then close up again, so that 
they take turns, when things are quiet, at letting blood 
through and only a few are open at any one moment. But as 
the observations on muscle show, they can all be opened 
when necessary at the same time and then opened much 
more widely so that blood races through them in much 
greater quantity. To make this possible the muscle in the 
walls of the appropriate arterioles relaxes at the same time 
so as to release more blood from the arterial reservoir. When 
the active organ in which this is happening is a small one 
or the movements to be carried out involve only a few small 
muscles, as in knitting, writing or quiet talking, the deple- 
tion of the reservoir is almost negligible and no further 
adjustments are necessary. But in severe muscular exertions, 
when nearly all the muscles of the limbs and trunk are in- 
volved, contracting and relaxing rapidly and repeatedly, the 
number of arterioles that dilate and of capillaries they have 
to fill may become very large; the reservoir then is in danger 
of being seriously depleted so that the pressure in it would 
be insufficient to drive the blood through the minute tubes. 
But when things are working properly nothing of the kind 
occurs. To begin with, as many as possible of the other out- 
lets from the reservoir are shut down, because the arterioles 
to parts which at the moment need not be working contract; 
blood is then diverted from them to parts where it is needed 
in greater amount. But much more important than this, the 
blood rushing through the muscles in vastly greater quantity 
than before is hurried back to the heart much more quickly, 
and the heart is a pump so made that the fuller it is the 
more powerfully it works, and so controlled by the nervous 
system that the more rapidly it fills the more frequent its 
stroke. The rate at which the arterial reservoir is filled by 


the heart is thus increased in proportion as the rate at which 
the blood is allowed to escape from the reservoir rises, and 
the net result may be that the head of pressure in it is actu- 
ally higher, not lower, than before, and the amount of blood 

put into circulation by the heart in a minutue may go up 
i_ r J - v i ; r r 

tronr perhaps five or six litres a minute to thirty or forty. 

This final result is attained, then, by a quicker return of 
blood to the heart and a correspondingly quicker and 
stronger action of the heart. The quicker return is mainly 
accounted for in two ways. First, the veins by which it has 
to be conveyed are compressed as the contracting muscles 
swell and harden against them, and rapidly filled again as 
these muscles a moment later relax to let their opponents in 
their turn contract in all such alternating movements as 
swimming, rowing and running. In the veins thus alter- 
nately compressed and allowed to fill there are valves which, 
as Harvey first made clear, ensure that no blood is pressed in 
the wrong direction, all must go towards the heart. Secondly, 
the carbonic acid, as well as sometimes other acid, produced 
by the working muscle acts on the part of the brain that 
works the muscles used in respiration and causes much more 
vigorous movements of the chest. The greater expansion of 
the chest not only draws more air into the lungs through 
the windpipe, but, since the heart is in the chest no less than 
the lungs, draws blood into the heart from the veins on their 
way to the heart from other parts of the body. At the same 
time the diaphragm between the chest and the abdomen, as 
it descends in inspiration, enlarging the capacity of the 
chest and diminishing that of the abdomen, forces blood 
from the abdominal veins up into the heart. The muscles, 
by going into action, themselves set in motion machinery 
for promoting a much more rapid flow of blood to the 
heart, and so increase their own supply. 

Similarly, the quicker return of blood to the heart brings 
into operation a property of the muscle of which its walls are 
composed, namely, that when more stretched it contracts 
with greater vigour than when less stretched. A full heart 
responds to the increased demand made upon it and expels 



more blood at each stroke. This property of the cardiac 
muscle operates within fairly wide limits, but not without 
limit. An over-full heart may be embarrassed by too great 
distention. Over-filling of the heart, however, is provided 
against by yet another adjustment. Nerves in the part of the 
heart which receives the blood from the veins are stimulated 
when this part of the heart is stretched. These nerves act on 
the cells in the brain that control the rate and force of the 
heart beat, and release it from the restraining influence which 
these cells otherwise exert. As a result of this it is quickened 
and beats perhaps more than twice as frequently as before. 
At the same time, since the blood is returning much more 
than twice as rapidly as before, it fills up even in the 
shortened intervals between its beats much fuller than be- 
fore. Its beat consequently is, for the reason mentioned 
already, at the same time stronger, and its total output per 
minute may be five or six times what it was. 

All this is one of the commonplaces of physiology, but 
there is no better illustration of the way in which many dif- 
ferent parts and organs of the body are brought into action 
together, each doing what it can and must, to increase the 
efficiency of the whole. Even in present-day civilized condi- 
tions a man's life often may depend on his power to make a 
great and sustained effort; and it must be remembered that 
his power of doing so was acquired long before there was any 
question of civilization, when this power had to be called 
into play daily and hourly if he was to survive at all. Nor 
are the reactions involved even peculiar to the human body; 
the adjustments are the same in other mammals, and know- 
ledge of them has actually in the first instance been obtained 
from experiments on rabbits, dogs and cats, many of them 
even from experiments on animals as remote from man as 
frogs, much older than any mammals. 

In this combination or co-ordination of the activities of 
different parts for a common end, the several parts are 
brought into action at the appropriate moment largely 
through the nervous system, which is the supreme co-ordi- 
nating mechanism of the body. The whole outbreak of 


activity may be started by something seen or heard which 
sets the brain to work; the brain, acting through other parts 
of the nervous system, brings the appropriate muscles and 
combinations of muscles into action at the right moments 
and with the right degree of force. The control of the escape 
of blood from the arterial reservoir, and the control of the 
rate and force of the heart beat which fills the reservoir, is 
effected by the nervous system, as is also the rate and depth 
of respiratory movements. But in addition to that, sub- 
stances formed in active cells may act as co-ordinating 
chemical stimulants on other cells to which they are con- 
veyed by the blood or which they reach by diffusion in the 
liquid which fills the interstices between cells everywhere in 
the body. The opening up of the capillaries running along the 
muscle fibres is effected by substances produced in the 
muscle fibres when they contract. The same substances, or 
some of them, conveyed by the blood to the brain increase 
the activity of the part that rhythmically works the respira- 
tory muscles. An important part is played, too, by a sub- 
stance produced in the little suprarenal glands where there 
are cells that have, so far as we know, nothing else to do but 
make the substance adrenaline. This substance tones up the 
influence of a part of the nervous system which is specially 
concerned with the heart and arterioles, but also with most 
viscera, and so the heart is quickened and invigorated, some 
arterioles are dilated and equally appropriately others con- 
stricted, the spleen is made to yield some of its reserve of 
blood, the activities of the stomach and intestine suspended; 
in short, everything throughout the body is so set as to give 
the working muscles the best chance of showing what they 
can do. 

In every chapter of the physiology of higher animals and 
man a story is found as amazing as that which the study 
of the circulation presents : cells, all of them derived from 
one common parent cell taking up as the organism grows 
definite positions, the same in each generation; there de- 
veloping special properties by virtue of which each kind of 
cell can co-operate with its fellows in its own specific way for 


their common well-being, and each adjusting its activity ap- 
propriately to the changing needs of the whole society of 
which it is a member. 

Just as we often speak of the material in which the pheno- 
mena of life are exhibited as living matter, we may with as 
good reason speak of an organism as a living machine. A 
machine is constructed so as to work in a certain way; its 
design may provide automatic adaptation to changes in the 
conditions in which it may have to work. Gears may be 
changed automatically; a loom may stop itself while it re- 
pairs a broken thread; a chronometer compensate for 
changes in temperature. That has all been thought out 
beforehand in the design of its construction. 

These are figures of speech. To speak of living matter is to 
31ur over the fact that all other matter is lifeless, dead as a 
stone; this is matter that is alive. Recognition that the ele- 
ments in it are among the commonest components of the 
lifeless earth and air merely emphasizes that the mystery of 
why it is alive has not been fathomed. Biochemistry has a 
high-sounding name. But chemistry, the science that defines 
the groupings into which atoms fall and the properties those 
groupings confer on lifeless matter, when it assumes this 
name does not claim that it can explain the chemistry of 
life. If anyone is led by all he hears of the triumphs of bio- 
chemistry to imagine that that problem has been solved it 
would be a case of the blind not knowing that they were being 
led by the blind. It is not that the biochemists themselves 
think they can see. They do not pretend to define the chemi- 
cal constitution of the material of the germ cell, a speck of 
matter too small to be seen without a microscope, which 
in appropriate surroundings will produce a progeny of a 
hundred different types of cells, millions or billions of each 
kind so distributed and with such properties that the whole 
organized society which that progeny forms may reproduce 
a likeness of the parent organism from which the germ cell 
sprang. Not merely an anatomical likeness, the same num- 
ber of fingers and toes and ribs, jointed in the same places 
and in the same ways, nor one confined to material resem- 


blances, colour of eyes or hair, but a functional likeness. A 
baby does not have to be taught to crawl or sneeze or smile. 
A child may grow to resemble a grandparent or an uncle it 
never saw in quality of voice and intonation, facial expres- 
sion, carriage and movements. Something in the chemical 
constitution of that microscopic speck of matter has directed 
the growth and grouping of its progeny of cells, nerve cells, 
muscle cells, bone cells and the rest, so exactly that the whole 
resulting organization walks, talks and laughs in recogniz- 
ably the same way as did the organization that grew from 
another such speck and became the child's grandfather or 
uncle, differently from others of different parentage. 

So, too, therefore, when we speak of the machinery of the 
animal body, of its organs of circulation or respiration, it is 
a form of speech that may be misconstrued. It does not 
imply that the design of its structure and every readjustment 
of which it is capable is once for all provided for in the 
original, rigidly according to specifications. In course of 
time living organisms can change their design, their struc- 
ture and function, so that they may meet changes in their 
circumstances that they have never had to meet before. The 
machinery is alive and readapts its own design according to 
changes in its circumstances. 

When a type of organ is common to different divisions of 
the animal kingdom and not found in the rest, it is probable 
that these divisions that have it have a common ancestry. It 
is easier to suppose such a common ancestry than to suppose 
that that type or organ has appeared independently at dif- 
ferent times in different classes of animals. The common 
features of the spinal columns of all vertebrates are thus 
taken to mean that all vertebrates have common ancestors; 
and the peculiarities in the composition of their blood com- 
mon to them all point to the common ancestors having lived 
as marine animals at an early period in the history of the 
earth. The special properties of the nerve cell point to a 
common ancestry not only for all vertebrates but for many 
other large classes of animals as well. From very early days 
in the history of life the organ which in its perfected form 


has given man his pre-eminence has been in the service of 
animals. But the nervous system has modified its design in 
man so as to react in many ways in which in the snail it does 
not, and in the snail in many ways in which it does not in 
man. Throughout the evolution of higher types the living 
machinery has become sensitive to more and more factors 
in its environment and readjusted itself to changing circum- 
stances of climate, food supply and competition. All this has 
been done as part of the natural reaction of what is alive, not 
deliberately as the result of forethought or conscious volition. 
The evidence for such evolution is, of course, mainly in- 
ferential, but it is strong. Physiology looks forward to the 
day when experimental evidence may be obtained from its 
study of living cells and their chemical anatomy which will 
make it possible to understand how such a living mechanism 
as that by which the blood is circulated in a man's body has 
been perfected in the performance of the service which it 
renders. Most of the experiments it has devised hitherto 
have been planned to show how the machine in any par- 
ticular species works. All of them have revealed an amaz- 
ingly appropriate adaptability to the changes that constantly 
recur in the needs of the individual. But it is on the lookout 
for methods by which it may learn how the adaptations of 
design that are characteristic for any species are brought 

Such investigations must entail the study not only of in- 
dividual animals, but of long series of generations. A begin- 
ning was made in Pavlov's well-known experiments in which 
he showed that a dog's experience may bring into existence 
a reaction which otherwise does not occur in a dog. Its 
salivary glands are normally set in action by nerve cells in 
its brain, which in their turn are set in action normally by 
nerve cells connected with its nose or mouth or eye, which 
react to the smell, taste or sight of appetizing food. But 
other nerve cells connected with its skin or ear, capable of 
giving rise to sensations of touch or hearing, may acquire the 
power of activating the cells that start salivation if some par- 
ticular one of these sensations is set up by, for instance, the 


regular use of a bell at feeding time. At first the sound of 
the bell by itself has no effect on the salivary glands. But 
after it has been sounded daily when the animal is fed a 
time comes when the sound of the bell by itself is as effective 
in starting a flow of saliva as the smell or taste of the food 
it enjoys. The nerves of smell and taste are connected up in 
all dogs with the cells that start salivation, but in the dogs 
used in these experiments it has been possible to establish a 
similar connection also for nerves of hearing or touch, a con- 
nection which did not exist before. A new anatomical struc- 
ture has been brought into existence as a result of a change 
in the circumstances of the animal's life. Pavlov, moreover, 
thought at one time that he had evidence to show that in 
succeeding generations of dogs the sound of the bell became 
effective in a much shorter time; but he decided later that on 
this point the evidence he had obtained was not satisfactory. 
More recently, however, Macdougall has shown convincingly 
that rats respond in a certain way to a warning light at the 
third or fourth trial in the twentieth generation, whereas 
twenty generations back the response could not be obtained 
till after two hundred trials. Apparently the experience not 
only of the individual but of its ancestors can cause nerve 
cells to grow in a particular way in which otherwise they do 

A new function involving a change in the design of ner- 
vous machinery has been brought into existence as the result 
of a reaction of the living machine to external events. This 
particular reaction does not affect the chances of survival of 
the dog; there is nothing gained by it; it is just superfluity 
of vitality. But so long as the change in external circum- 
stances persists the reaction persists; and if it were a useful 
reaction it would make for survival; moreover, if Mac- 
dougalFs experiments stand, the new machinery would be- 
come part of the machinery of the species. 

It is not, therefore, only the extraordinary complexity and 
extraordinary appropriateness of design in living machinery 
that physiology has to study; it has also to observe and ex- 
plore the ways in which the design grows and develops. 


The secretion of saliva is not a voluntary act: it takes 
place without the dog knowing anything about it. One o 
the reasons why it is difficult for anyone who has not studied 
physiology to understand how that study can affect his out- 
look on the world is perhaps this. He knows that it deals 
with what goes on in his body. Most of what he knows about 
this to start with is that of which he is conscious. He is 
accustomed to manage his own life and to decide how he 
will occupy himself from minute to minute throughout its 
course. He has to learn how much more there is of what goes 
on in him of which he has no conscious knowledge, and how 
much more appropriately this is done as a rule than what he 
himself consciously plans. It is only a very small part of the 
activities even of his brain in which he is, so to speak, con- 
sulted. Far the larger part is just the working of the living 
machinery that has cunningly adjusted itself to the experi- 
ence of his race and species, and of ancestors far further back 
than his species or any living species can be traced. Every 
posture is arranged and appropriately maintained, every 
simple movement is carried out for him by chains of co- 
operating cells with a precision and economy in which con- 
sciousness has nothing to say. The machinery has been per- 
fected because it is alive, not because it is conscious of what 
it has to do. Even in the skill of an accomplished singer or 
billiard player there is comparatively little that is due to con- 
scious volition. Otherwise it would be far easier for such 
people to impart the mystery of their skill. Consciousness is 
for psychology to study; it is outside the province of physi- 
ology. Physiology regards consciousness merely as one might 
regard the impresario who arranges the programme. What 
it is interested in is the artist and the music he draws from 
his instrument. In the skill of an artist it recognizes a self- 
adjusting living machinery, such as is found in whatever is 
alive, in which consciousness plays as much or as little part 
as it does in the easy certainty with which a cat jumps on 
to a wall, in the gambols of a school of porpoises, or in the 
flight of gulls and swallows. Consciousness makes fools of 
us all; for there is no folly greater than to suppose that what 


we know is all there is to know. That folly is the first thing 
a schooling in physiology corrects. 

But few have time or opportunity to attend this school. 
What the majority of men can pick up of physiology is 
seldom more than a third-hand familiarity with some of its 
terms. They learn to talk, for instance, of reflex action, which 
they are content to define as an unconscious act of a man or 
animal, a definition which conveys almost nothing but com- 
plete ignorance of what a reflex really is. It is common to 
talk with easy assurance of a reflex as if it were some sort of 
clockwork mechanism that might shortly be purchase- 
able for a few pence at a toyshop, as if the recognition 
of the part played by reflexes in ordinary human life had 
cleared up all that is mysterious in it except perhaps con- 

A reflex implies, to begin with, a nerve cell from which 
has grown out a projecting filament or feeler to a distance 
generally out of all proportion with the ordinary dimensions 
of cells. Animal cells rarely measure more than i/sjoth of 
an inch in any diameter; this feeler may in a man grow out 
to a distance of three or four feet from the cell of which it 
is functionally and by origin a part. Stripped of the invest- 
ing sheath which other cells deposit around it, it is never 
more than i /5,oooth of an inch thick. Its length, therefore, 
may be 200,000 times its diameter; magnified to the thick- 
ness of a piece of sewing thread, say i/5oth of an inch, its 
length would then be anything up to a hundred yards. The 
direction in which it has grown, and the connections which 
it and its ramifications have established, are those which 
have been characteristic of a similar cell in the man's ances- 
tors for thousands of generations. At the extremity of this 
feeler or of one of the still finer spreading filaments into 
which it frays out before it finally terminates, some displace- 
ment, it may be of only an adjacent molecule, or atom or part 
of an atom in a molecule, brought about by something it 
may be as impalpable as light, sets up a change which is 
flashed along the whole length of the filament up to its 
parent cell. The change which passes along the filament 


travels at the rate of about a hundred yards a second, but 
what exactly it consists in is still not understood. It is called 
a nerve impulse, appropriately enough as the name conveys 
nothing in particular; nothing like it is known. This im- 
pulse, or more often a rapid series of impulses, reaches the 
cell and passes on along another filament that has grown 
from the cell in the direction of the mass of nerve cells that 
constitutes the spinal cord and brain. Here this filament 
frays out into a number of finer fibrils each of which ends in 
the immediate neighbourhood of the feelers of another nerve 
cell, one fibril those of one cell, others those of others. In 
these feelers the nerve impulse can awake on its arrival a 
similar impulse, which is then in its turn flashed to the 
furthest point of the filament thrown out by this cell; and so 
on, it may be through a whole concatenation of cells, all of 
them within the brain or spinal cord. Sooner or later the 
feelers of cells are affected from which filaments pass out and 
convey the impulse in them to cells of another kind, muscle 
cells or gland cells, and then the appropriate activity of 
movement or secretion is set up; for the nerve impulse can 
do this too. Every section of the route travelled by the reflex 
has to be composed of " living matter " keeping itself alive, 
taking up oxygen and recovering from the disturbances that 
pass along it; every molecule or fragment of a molecule, 
along a path that may possibly measure some feet in length, 
must know its place and observe its station. Such is the 
mechanism of a reflex. Physiology has rendered no great 
service if it has taught people to talk glibly of a reflex as if 
it were some simple clockwork contrivance. 

Most people have heard something of astonishing achieve- 
ments of biochemistry in tracking down, isolating or even 
finally manufacturing substances which are normally pro- 
duced by cells here or there in the body and which exert 
extraordinary powers in directing development or influenc- 
ing conduct. In the proportions in which they are normally 
produced they contribute to the balance of influences which 
results in normal growth of body and mind; in abnormal 
proportions they lead to loss of balance. Or they may have 


heard how other disturbances of this balance have been 
traced to excess or deficiency of some factor in the environ- 
ment, including in this expression food, the components of 
sunlight and so forth. Even when such information is per- 
fectly correct it may often be so novel and surprising that 
they are in danger of losing their sense of perspective, unless 
their study of physiology has been broader and deeper than 
with the majority it can be. They are apt to forget that one 
of the things the investigator in pursuit of new knowledge 
has to do is to exert his imagination and catch at and test 
even the faintest clue. It is the investigator's business to 
make the utmost possible use of ideas in which only a small 
fragment of the whole truth may be contained. The sus- 
picion with which probably most people regard the specialist 
is not altogether unhealthy. There is always the danger that 
his disciples, if not the specialist himself, may become prigs; 
ignore, that is, what they don't know and exaggerate the 
significance of what they do. New knowledge in itself is a 
factor in the environment of human life to which adjust- 
ments have to be made, and in all probability the best part 
of the adjustment will not be the result of conscious plan- 
ning. Life has looked after itself for hundreds of millions 
of years without the assistance of what can be recognized as 
consciousness, done it extraordinarily well and continues to 
do so still. 

It should not be regarded as a trespass on to other fields 
than that of physiology to refer to a faculty of the human 
body which history can prove to be in process of develop- 
ment today. The history of music goes back, no doubt, tc 
the earliest historical times, yet the material for that history 
is so scanty that it makes but a small chapter in the history 
of civilization. For the physiologist the two outstanding 
phenomena in it are the development in the Greeks of a 
sense of rhythm that has not been approached by an} 
civilized people since, and the growth of the sense of har 
mony in the last few centuries. 

The Greek sensibility to rhythm in all its richness anc 
diversity was fortunately developed before facilities for writ 


ing. It could not have been developed after the invention of 
the printing press. The written records of literature de- 
throned the ear and put an end to the growth of the sense 
of rhythm. The record of rhythmic phrase was for the 
Greeks in the mind, played upon by sensations of rhythmical 
sound and sensations of rhythmical movement. The play of 
these sensations in the living nerve cells brought into being 
a considerable part of man's brain. It produced the faculties 
that have found expression in poetry, besides the music of 
three thousand years since this sensibility attained its per- 

In our own day the growth of the sense of harmony is the 
most striking example of the physiological process of un- 
conscious growth and perfection of a functioning organ. 
Quite recently perhaps in the i5th century the third was 
a discord and the octave and the fifth the only tolerable har- 
monics. The ear has gradually quite unconsciously recog- 
nized since then many other harmonics that may accompany 
a particular note on a particular instrument, and has taught 
responsive reflexes to play with what it has come to hear. 
This growth of harmonic sense owes little if anything to 
deliberate scientific planning. 

It is like the processes by which we acquired ages ago the 
system on which we depend for the circulation of blood with 
its myriads of corpuscles bringing oxygen and food right up 
to every cell in our bodies, a system which in essentials was 
perfected for us when there was nothing higher than a fish 
inhabiting the earth; it is like the processes still much further 
back in the history of life when nerve cells were learning to 
make themselves useful to the community of which they 
form a part, an instance of the self-perfecting powers of 
* living machinery/ 

Life is something much bigger than human consciousness. 

And what does it all mean for us? Can we do no more 
than exclaim, ' No wonder if with such antecedents half the 
human race, or all of it, still has traits that it shares with the 
shark, the wolf, and the pig'? Does it mean no more than 
that? Is it no wonder that from this ancestry in recent 


times have sprung the glorious company of the poets, Homer 
and St. Francis, Hans Andersen and all the goodly fellow- 
ship of the prophets, the noble army of martyrs, and only 
yesterday the unaccountable inspiration of music? All this 
has to be remembered and is implied when we speak of 
" living matter/' 



Sometime V ice-Chancellor of the University of Bristol 

THE question : What is the Outlook of Science? raises 
the prior question : How is ' science ' to be defined or 

It may be said : Surely this or that science may be defined 
in terms of its subject-matter; for example, mathematics, 
geometry; physics, chemistry; biology, psychology. Here, 
apart from some overlap, the question is : What is the aim 
of this or that scientific inquirer? Taking, for example, two 
salient cases, we may ask : What is the physicist's aim? What 
is the aim of the psychologist? If we can catch them at work, 
each in his own chosen field of inquiry, we may be able to 
judge for ourselves. 

The stress may then fall on scientific method. Scientific 
method is the means by which the physicist, the psychologist, 
or other man of science, attains the aim which is the goal of 
his inquiry. But what is this goal? It may be to render an 
account of what happens on some occasion and on all like 
occasions in physical terms, or in psychological terms, within 
a ' closed system ' of events or occurrences, physical on the 
one hand, mental on the other hand. 

Can this be done in physics and in psychology respec- 
tively? It suffices to say that it has been attempted. 

There are those who contend that, on the physical side of 
the account, this attempt has been successful. It is clear 
that, apart from some apprehending mind, the physical world 
is nowise apprehended. But it does not follow that, apart 
from any apprehending mind, the course of physical events 
is not there all the time to be apprehended on suitable occa- 
sions. This question, therefore, does arise : Is the current 
course of physical events the same in all respects and on all 



occasions, whether it be apprehended by some mind or not? 
The physicist may claim that it is; otherwise, he may say, 
there would be no closed system of physical events. 

But when we turn to apprehending and to what is appre- 
hended on the part of some mind when we turn to know- 
ing and what is known this comes, it may be said, within 
the purview of psychology. We pass outside the boundary 
line which circumscribes physics. 

On these terms the psychologist may seek to make out a 
case for a closed system of mind with which it is his special 
province to deal. In what follows an attempt will be made to 
discuss the outlook of psychology on the assumption that, as 
a branch of natural science, it is primarily concerned with 
mental occurrences as its sister science is primarily concerned 
with physical events. 

If there be a closed system of physics, and a closed system 
of mind, each may be discussed in abstraction from the other 
so long as neither physicist nor psychologist trespasses out- 
side the bounds of his own special province. 

But when the day's scientific work is over, they may ex- 
change confidences in the evening. Each wants to know what 
the other has been doing in his day's work and thought. How 
far will they get if either says to the other : Those relations 
which fall under the heading of space and time lie wholly 
within my province, and do not come within yours? Must 
they not agree that in some way spatio-temporal relatedness 
is common to both provinces? 

If, however, ' space-time ' is in some way common to both 
provinces, does not that annul the distinction between the 
two closed systems? On further consideration they may 
agree that it need not do so. You, says the psychologist, deal 
with space-time ' as it is/ whether it be apprehended or not. 
I deal only with ' ideas ' of space-time as they take form in 
some mind. Your ' space-time ' is outside my closed system; 
my ' space-time ideas ' are outside your closed system. So, 
too, your ' physical events ' are outside my closed system; my 
'ideas' with reference to physical events are outside your 
closed system. 


We are talking of our day's work. each in his specialized 
province of science; let us say * in single regard/ But now we 
compare notes in the evening; let us say ' in double regard/ 
Moreover, even during the day, each holds the other's regard 
in the background of his thought since neither denies the 
other's closed system. 

It seems then that in double regard we discuss such ' points 
of contact ' as there may be between the two systems, or, in 
more technical phrase, such * co-relation ' as may obtain 
between them. One field of joint inquiry in which such co-re- 
lation seems to be conspicuously in evidence is that which we 
speak of as ' sensory perception/ 

In this field the physicist deals, let us say, with a ruby; and 
in this field the psychologist deals with the ' idea ' of the ruby. 
It may then be asked: Does this idea in someone's mind 
' represent ' something which goes on in the physical ruby? 

They may agree that in some sense it does, but may elect 
not to use this word lest it should be taken to imply ' resem- 
blance/ So they ask leave to substitute the less familiar word 
* co-relation,' which is to imply that, so far as it obtains, if one 
can tell what goes on in this closed system one can infer what 
goes on in the other. What does go on in either system de- 
pends on the relational context, physical or mental, as the 
case may be. 

Thus far physicist and psychologist talk matters over in 
the evening as colleagues in science. They may, however, be 
joined by a third party one who claims to stand for philo- 
sophy which, he may say, includes science, but comprises 
more than science. 

I have listened with interest, he may say, to your conversa- 
tion; but from my point of view there is somewhat lacking. 
I hear no mention of that which you will perhaps allow me 
to speak of as Activity. You describe what happens on some 
occasion, or on all like occasions, and you discuss the * rela- 
tions ' and ' co-relations ' which, as you put it, * obtain ' on 
such occasions. You say nothing about what causes anything 
to happen as it does happen. That is what I mean by Activity. 
You both speak, as I understand, of * organization ' physical 



or mental, as the case may be. But can there be organization 
in the absence of some directive Activity that organizes? In 
brief, your aim seems to be to render in generalized terms ' an 
account of ' what happens; but my aim, as philosopher, is ' to 
account for 9 what happens. What say you, Mr. Physicist? 

I can only speak for myself, he may reply, for we are not 
all agreed. I am one of those who, without denying Activity 
(Force as Cause in the mediaeval sense), have no use for it in 
my closed system. My aim not only ' seems to be ' but is to 
render ' an account of ' what happens in purely relational 
terms. It is not for me to ' account for ' it. But on this head 
our friend the psychologist may have something to say. 

I agree with my colleague the physicist. I, too, have no use 
for Activity in my closed system. There are, however, many 
psychologists who regard creative and directive Activity as 
the pivotal factor in this branch of science. They urge that 
its inclusion radically distinguishes the science of psychology 
from that of physics. Hence it is incumbent on any writer 
who deals with science to state clearly what he includes 
therein and what he excludes therefrom. Let me, then, say 
frankly that in what follows I do not include Activity within 
the closed system of psychology. I regard it as distinctive of 
the realm which lies Beyond science. Therein I assign to it 
that which I deem to be its true metaphysical status. Is this 

The plain man likes to start from the platform of common 
sense and quotes with approval the dictum that science is 
trained and organized common sense. He may, or may not, 
pause to ask : When in the course of his life-history did he 
reach this platform? Did he step on to it at birth; did he 
reach it in his cradle days; or not till in years he was 3^, or 
7, or 14? This is a psychological question. It deals with the 
development of the human mind. 

In any case waiving the question as to how we come by 
it we are prone to talk glibly about * simple common sense '; 
but when we come to grips with it we find that it is exasper- 
atingly complex. 

So we try to simplify it as best we can. And then perhaps 


we say that it reduces to this : The plain man has been led 
to recognize, (i.) a material world of which his body is part; 
(ii.) minds, his own and those of living beings other than him- 
self; (Hi.) Activity or Agency exercised by Somewhat' or 
'someone/ For the plain man these three afford an irre- 
ducible minimum. Not one of the three can be dropped out 
of the reckoning. 

No doubt this is over-simplified. It takes no explicit ac- 
count of time or of place. But for the plain man changes of 
time and in space are so obvious that they are commonly 
taken for granted. In due course, however, he is led to realize 
that just here, in these space-time problems, lies much that is 
crucial for modern thought. 

Let us assume, then, that matter, mind, and activity are 
three main planks in the common-sense platform. If the 
plain man join in the talk between physicist and psychologist 
he insists on three-fold regard. And they, too, may (or may 
not) then agree to include Activity, though each excludes it 
from his special work-a-day inquiry. 

From this three-fold platform the plain man may plunge 
into the sea of philosophical literature. Let us suppose that 
he elects to dive into the past some 250 years ago, so that he 
may compare what was said then with what is being said 

It may strike him that within five years there appeared 
three works Leibniz's Petit Discourse (1686), Newton's 
Principia (1687) and Locke's Essay (1690). The voices of 
these three great men he still hears re-echoing today. Pro- 
fessor Wildon Carr's Cogitans Cogitata is a Leibnizian 
monadism brought up to date. Professor Einstein proclaims 
a transfigured Newtonian physics. In Professor Whitehead's 
Process and Reality, Locke's thought is conspicuously in 

He who bathes in such philosophical waters is no longer 
the plain man that he was. Not improbably, however, he 
cherishes a core of common sense. He is still, therefore, likely 
to ask: What about matter, mind, and activity? He may 
say : In monadism matter, in independence of mind, seems 


to have been served with notice to quit. There remains only 
the Activity of monadic ' minds/ In modern physics matter, 
under some new guise, say, wave-mechanics, seems to occupy 
the whole field. Mind save as occasional onlooker has been 
given notice to quit. So, too, has Activity. 

Thus far, in the strictly closed system of psychology as a 
science of mind and that is what we want to get at we 
may say : Exit physics. It is relegated in science to a closed 
system which this or that human mind contemplates. And, 
thus far, monadism is a closed system of purely mental re- 
lations with emphasis on Activity to account for all that 

What then of Locke? In his capacity as psychologist he 
championed a 'doctrine of ideas/ And for him all ideas, 
whether they * come from ' sensation or reflection, are purely 

But, in double regard, the ideas which come from sensa- 
tion indicate the presence of * sensible objects ' which have 
* qualities ' such as shape, hardness, and colour. 

Locke and his reader then get into difficulties since ' ideas ' 
and ' qualities f are often so spoken of that it is hard to say 
which is meant. Let us therefore leave seventeenth-century 
Locke and exchange notions with his twentieth-century 
reader. Then, keeping to Locke's terms, this thesis may be 
submitted for consideration. Sensible objects, as such, and 
all their qualities, lie wholly within the closed system of 
physics; all ideas, as such, lie wholly within the closed system 
of psychology; Activity, as such, lies wholly Beyond either 

According to this thesis we all start, as plain folk, with some 
such common-sense notions as matter, mind, and activity, 
Locke unquestionably did so. He was only feeling his way 
towards a clear distinction between sensible objects within an 
abstract system of physics, and ideas within an abstract 
system of psychology. He retained the common-sense notion 
of activity or power. Berkeley held fast to ideas, but denied 
that they indicate anything material or physical. For him 
the sensible object just is a cluster of ideas. He held fast also 


to spiritual Activity. Hume, though he drew a subsidiary dis- 
tinction, purely psychological, between * impressions ' and 
* ideas/ sought always (in the study) to keep within a closed 
system of mind. And in his polemic against causality he 
resolutely banned all reference to Activity. 

Along this historical line of advance, carried farther, we 
reach a closed system of psychology as distinguished from a 
closed system of physics. Activity lies Beyond the purview 
of either closed system. 

Let me use the word * Beyond' for that which may be 
reached by transgressing the ' methodological ' boundary 
between science and philosophy; and the word 'outside' for 
that which is reached in passing from this to that province of 
science say, from psychology to physics. Locke passed 
freely to and fro across the latter frontier. And few men of 
science today refrain from doing so when they prosecute 
inquiry within both provinces of science in their double 
capacity. In this sense they may say that what as psycholo- 
gists they deal with as ideas ' in mind ' are for them as 
physicists certain co-related qualities in sensible objects or 
external things. 

The question then arises: Can we say that any idea in 
mind ' resembles ' a quality in the sensible object? Locke, 
in effect, replies : Yes; at any rate in some cases. His belief 
(in line with that of sundry predecessors, Galileo, Boyle, and 
others) was that some ideas do resemble, whereas other ideas 
do not resemble, though they ' correspond to,' the ' real ' 
qualities of sensible objects. It seems then that only through 
these resemblant ideas do we learn the nature of sensible 
objects as they are ' in themselves/ 

Locke's successors have again and again discussed the 
validity of this distinction between 'primary' and 'secondary ' 
qualities. Berkeley long ago denied its psychological validity. 
Professor Whitehead today, on the basis of direct apprehen- 
sion, denies its physical validity. It may perhaps be said that 
both parties meet on common ground in so far as the one 
brooks no ' physical additions/ the other no ' psychic addi- 
tions/ to his closed system. 


But on these terms there seems to arise a serious deadlock. 
For the plain man is convinced that there is some connection 
between the qualities of things and the ideas which indicate 
their presence in these things. 

It remains, then, for the physicist and the psychologist in 
joint session when they regard each closed system as in 
some way complementary to the other to suggest an avenue 
of escape from this dilemma. The outcome may be that the 
co-relation between the two systems is such that, given all 
that is in mind, the physicist could infer what relevant 
physical events are in progress including of course those in 
body and brain; and that given these physical events the 
psychologist could infer all that is then in mind. 

In a closed system of physics, inquiry is restricted to 
physical relatedness (relations and relata) within a frame of 
physical space-time. Similarly in a closed system of psy- 
chology inquiry is restricted to mental relatedness within a 
frame of space-time ideas. But in joint session men of science 
discuss the evidence for co-relation. 

Let us now accompany the psychologist in his day's work 
on the assumption that, in * singular' regard he prosecutes 
his task within a closed system of mental relatedness. He 
has, let us say, a ruby before him. What is it for him as 
psychologist? A pretty complex idea to which there is on 
his part mental reference set in a context of other such rele- 
vant ideas. And what is he? When he reflectingly thinks 
of himself ' he ' is the very complex idea to which, in thus 
thinking, there is mental reference on his part. 

One is dealing with one's own reflective experience, and 
taking such interplay of ideas as one finds; and what one 
commonly finds is subtly varying reference to the idea of 
oneself as having in mind reference to ideas of surrounding 
things and events. 

Thus stated this may sound rather awkward. But it is 
among the commonest and most familiar of occurrences. 
For example, one has an idea of oneself seeing the ruby yes- 
terday or tomorrow. That, however, introduces retrospective 
reference to oneself and the idea of the ruby in the past; or 


prospective reference to oneself and the ruby-idea in the 
future. It introduces the idea of ' time ' and if one ' pictures ' 
oneself as seeing the ruby on the ring-stand this morning 
and on one's wife's finger this evening that introduces the 
idea of place. 

We have, then, the ruby-idea, the self-idea, the time-idea, 
the space-idea, and many others. Thus the word 'idea' in 
this its most comprehensive sense means ' somewhat to which 
there is mental reference.' And outside, or Beyond, that 
somewhat ' in mind ' the psychologist, if he keeps within his 
closed system, does not pass. When he reverts to common 
sense, however, he always so far keeps ' double ' treatment in 
view as not to preclude reference to the co-related body and 
its physical surroundings. For the presupposition here is that 
he is also a physicist in some measure, and that, as physicist, 
he fully accepts that closed system also. 

None the less, in the foreground of his thought the psy- 
chologist keeps steadily in view occurrences within his closed 
system of mind. 

Within that system there are those factors in experience 
which, following Locke, we have called ideas such as the 
ruby-idea and the self -idea. But there are other factors in ex- 
perience. One is aware in seeing the ruby. One is aware in 
thinking of oneself. One is aware, too, in thinking of 
yesterday's self as having been then aware in seeing the 

The word 'awareness' is here used, qualified by 'in' 
(* awareness in ') to name some mode of experiencing. One 
such mode of experiencing is that of behaving. This, in 
double regard, is co-related with some bodily process in 
singular physical regard, which, as such, is outside the closed 
system of mind. Awareness in behaving and all other modes 
of awareness, are purely mental and primarily individual; as 
indeed is all experiencing. 

But if I see you, or an infant behaving, there is on my 
part no awareness in behaving on your part or his. It is you, 
or he, that may be thus aware. Still I confidently believe 
that you are, and he is, aware in so behaving. So, too, I con- 


fidently believe that you are, and he is, aware in seeing or 
in touching, or more generally in any such mode of ex- 

We here take over a common-sense belief which carries 
* pragmatic ' endorsement on the platform of each plain 
man's daily life. And though one may be assured on good 
authority that it is not susceptible of strict logical proof, 
still if one were stoutly to decline to do so psychology, as a 
science, would be in sorry case. For then each of us would 
be confined within the closed system of his own first-hand 
experience (solipsism). 

Let us accept this current belief. Then, to label what 
happens let us say : Each of us ' imputes ' to others, human 
folk and many animals, first-hand experience, in some 
measure like his own. And this is to apply, not only to 
awareness in behaving or in seeing but to the occurrence of 
ideas in any mind other than one's own. For if I may not 
impute to an infant awareness in seeing, on what grounds 
may I impute to him reference to anything seen, or indeed 
ideas of any sort? Such 4 imputation ' (as it is here called) is 
quite distinctively psychological. It has no place in a 
closed system of physics. But it extends the closed system 
of psychology to experience in other minds than one's 

It is questionable whether the word ' experience ' can be 
satisfactorily 'defined/ Let us regard it as distinctively 
mental; and for the rest let us be content to say to one's 
neighbour: You have long ago learnt what it is far better 
than anyone else can tell you. We may, however, now dis- 
tinguish (i) factors of awareness in 'feeling/ and (2) factors 
of reference to an ' objective field ' of ideas. 

To the objective field of ideas under reference we may now 
turn; and since our aim is to get down to fundamentals it 
will be well to start with what seems to be common to any 
mind at any stage of its development. We may start, then, 
with sensory experience. That may seem simple enough. It 
brings us down to such basal ideas as are ours by way of 
touch, taste, smell, hearing, sight. But under our sensory ex- 


perience some would include seeing the thing there, and 
having seen it then. Thus space-ideas, and time-ideas, are 
introduced. Let us, however, proceed analytically, and dis- 
tinguish space-ideas and time-ideas, respectively, from sense- 

In ' perception/ as this word is here used, these sense-ideas 
combine with space-ideas and with time-ideas. They enter 
into 'associative organization* and thus give new wholes 
which, as many believe, are, in their characterizing features, 
' more than ' that which is given in the algebraical summa- 
tion of their partial constituents. 

Speaking, for example, at the beginning of this century, of 
James Mill, Professor Hoffding says that, he "lays great 
weight on the point that . . . several ideas and feelings may 
enter into so intimate a union with each other as to become 
inseparable, while the new totality, thus formed, possesses 
qualities which are not possessed by any of the parts." " The 
new qualities of the product cannot be deduced from the 
factors." This feature of progressive organization whether 
it be spoken of as * heteropathic/ ' emergent/ ' holistic/ 
* organic/ or be called by some other name is emphasized 
by many thinkers today. It will be accepted here. 

Locke distinguishes those ideas which 'come by sensa- 
tion* from those ideas which 'come by reflection/ This 
implies that there are (at least) two levels of mind, unreflec- 
tive and reflective. 

Let us concentrate attention on the human mind as re- 
flective and return, later on, to the unreflective processes at 
subordinate levels. It is in the reflective processes of daily 
life that we find ideas of self, and a plan or frame of space- 
time ideas in which patterns of sense-ideas are set. It is here 
that we find ideas of past or future occasions; with retrospec- 
tive reference to an idea of self on some past occasion (re- 
flective memory); and with prospective reference to an idea 
of self on some future occasion (reflective anticipation). 

Is that all? No; far from it. The inter-relations between 
retrospective and prospective reference are very complex. 
Let us take some ordinary situation and psychologically dis- 


entangle some of the threads of its intncately interwoven 

I received, let us say, an hour ago a telephone message 
from a friend that he will call for me in his car for a run in 
the country. I now picture myself then in the past, receiv- 
ing the message with a : " Good; we'll take Bodiam Castle in 
our round. I want to see the water lilies in the moat." A 
moment later, with change of attitude, I picture myself then, 
in the future, seeing the water lilies with a: "Splendid. I 
thought so;" or a : " What a pity; not yet in full bloom." 
Even that is not all. When I picture myself then, in the 
past, ' he ' (my pictured self) is picturing himself then, in the 
future, at the moat-side. And when I picture myself then, in 
the future, looking over the water, * he ' then looks back on 
what in anticipation he hoped to see, with an : Even better 
than"; or a: "Not so good as." If the former there will be 
satisfaction; if the latter disappointment. 

We thus introduce ' affective tone/ pleasurable or the re- 
verse, of which this only need here be said, that it qualifies 
the total awareness sentient, perceptive, and reflective in 
the current experience of the time being. This statement 
should be checked in the light of each person's first-hand 

Let us now suppose that the incident is over as an affair of 
yesterday. One reviews it in retrospection, or let us here say, 
in 'reminiscence.' It clearly presupposes a space-time plan 
with self in the thought-picture. But within this schematic 
frame of mental occurrences we can distinguish and em- 
phasize two occasions, an earlier, on receipt of the message, 
and a later, at the moat-side. On the earlier occasion what 
is relevant in mind is anticipation with prospective reference 
to the later occasion. On the later, what is relevant is retro- 
spection with reference to the earlier. In reminiscence, then, 
one has both occasions under review, but each in relation to 
the other. One pictures oneself on the earlier occasion, as 
'wishing' to see the lilies; and as satisfied or disappointed 
on the later occasion. The wish, however, in picturesque 
phrase, has, under anticipation, subsequent satisfaction in 


view; it is a wish to be satisfied. The satisfaction has, in 
retrospection, the precedent wish in view. It is the satisfac- 
tion of that wish. 

One may say, then, that, at the level of reflection, there is 
no wish without some 'end in view' to be fulfilled, if all 
goes well, on a later occasion; and no satisfaction on this 
later occasion in the absence of some relevant wish on an 
earlier occasion. 

Let us here pause to ask : What exactly, in this reflective 
context, are we to understand by the word 'wish/ It here 
implies an end in view. This end in view is in the objective 
field of reference. But ' one wishes ' to attain it and thus to 
reap satisfaction. No doubt, that which one wishes to attain 
(sometimes spoken of as 'the objective'), may itself be 
called ' a wish.' We may, however, elect so to define it as to 
lay chief stress on the mental attitude of awareness in wish- 
ing. The emphasis then falls on this mode of experiencing 
on someone's part. It must be felt in first-hand experience 
that one may say what it feels like. 

One may fairly assume that we all do know quite well 
what it feels like as specific and sui generis in the mental 
life of reflection. With emphasis, then, on its distinctive 
character as a familiar mode of awareness we have a relation 
between someone wishing on an earlier occasion, and an end 
in view as the objective to be attained in some later occasion. 

This, for the psychologist, is a ' teleological ' relation. 

There can be no doubt that teleological relations obtain at 
the reflective level of mentality. But do they obtain also at 
levels below that of reflection? Is there always, on any ' this ' 
occasion, anticipation with prospective reference to an occur- 
rence on some future occasion. Here psychologists of different 
schools frankly disagree. An extremist of one school may 
say: Yes, always. All mental relations are au fond teleo- 

Other psychologists have been led to a different opinion. 
They say : Not always. They say that on those occasions on 
which they are themselves unreflective they find in their 
own first-hand experience no ^sufficient evidence of teleologi- 


cal relations with prospective reference to some future occa- 
sion. They find only one occasion, that of the now of the 
'specious present/ But, within the one occasion they find 
that which I ask leave to speak of as 'fore-experience/ It 
may, however, be said that so-called fore-experience itself 
supplies, nay is, the end in view. Is that so, however, if an 
end in view has reference to some occurrence on a subse- 
quent or later occasion? My finding is that unreflectively 
one does not think of a subsequent occasion. One is im- 
mersed in the current occasion. As I lift a glass of water to 
my lips I detect now, on this occasion, fore-experience of 
drinking before I actually do so, though reflectively I may 
also have the end in view of quenching my thirst as the 
result of drinking. The discussion seems thus to turn on the 
presence or absence of teleological relations in unreflective 
procedure a purely psychological question. And there we 
must leave the matter sub judice. 

One may, however, still ask : On whose part is there that 
anticipation, with prospective reference to some future occa- 
sion, which is essential to the very being of an end in view 
to be discussed under teleology? The reply may be : On the 
part of some individual mind as a unitary whole and not 
less than a unitary whole. Under imputation it is your mind, 
or that of Chica the chimpanzee, of Caesar the dog; of some 
cow, rabbit, frog, fish, lobster, earthworm, amoeba; in each 
case this or that mind one and indivisible. 

This is widely accepted. By the method of analysis, how- 
ever, the psychologist distinguishes a great number of wishes. 
He then proceeds to classify these wishes (this one word is 
here selected others such as * impulses/ ' instincts/ ' urges/ 
may be substituted at discretion); and he does so in accord- 
ance with their * outcome' in experience, imputed on the 
basis of behaviour. This inquirer may work with 6 classes; 
that inquirer with 12; others with less than 6, or more than 
12. Of each well-devised scheme one asks : Does it work? 

One cannot enter into details. What calls for emphasis 
here is that each several wish may thus be regarded as (or 
* as if ' it were) a ' monadic mindlet/ so that one may say : 


This or that monadic wish has this or that end in view, and 
plays its part in alliance with others that have a like end, 
or in conflict with others whose ends are different. 

The question then arises : If any given mind is a unitary 
whole, do not all the monadic wishes, as constituent factors, 
play their parts in subservience to, and never ' apart from,' 
that whole? Thereon the further question arises: May not 
this be subject to the 'organic' or 'emergent' principle? 
May not wishes " enter into so intimate a union with each 
other as to become inseparable, while the new totality thus 
formed " (ultimately the mind as a whole) " possesses quali- 
ties which are not possessed by " the wishes taken severally 
as parts? 

But question leads on to question; and this in due course 
follows: If the treatment is thus far monadic; and if in 
monadisrn the hinge-concept is Activity; has one not already 
passed beyond the closed system of psychology which, as 
such, is objectively restricted to 'ideas' in the mind? In 
much current 'doctrine of wish,' Activity is either overtly 
expressed or covertly taken for granted. 

Only under rigidly abstract treatment is there a closed 
system of physical events or a closed system of menta) occur- 
rences. On these abstract terms, however, there is neither 
give nor take between one closed system and the other. 
There are no 'psychic additions' to the one; no 'physical 
additions ' to the other. Nor is there ' interaction ' of one on 
the other. If there were interaction one or other system 
would no longer be closed. 

None the less there is, on this hypothesis, so intimate a 
co-relation between some physical events in the body and 
some mental occurrences that with regard to them either 
physicist or psychologist may say : If you tell me what goes 
on in your closed system, I can infer what, relevant thereto, 
goes on in mine, although physical relations and mental re- 
lations are quite different in kind and nowise interact. 

On the assumption, however, that there is no interaction, 
this co-relation must be accepted as we find it. All one can 
say is : Such is the constitution of nature. To account for it 


one must go beyond either closed system and invoke some 
Activity to which the ' harmonious ' organization in both 
systems may be due. 

That is what the plain man habitually does on the basis 
of common sense. He says: Your denial of interaction is 
merely a theoretical consequence of your abstract treatment 
under two closed systems, and of your refusal to entertain 
the concept of activity to account for the co-related organiza- 
tion in both systems. Against this he raises his voice in pro- 
test. You men of science, he may say, seem ' out ' to deny 
activity in any form. Here, if you will allow me frankly to 
say so, you are hopelessly * out of date.' Modern psychology 
has now reinstated activity; and one may see good signs of 
its reinstatement in modern physics also. 

To this the psychologist may reply : If you will allow me 
to be equally frank, you are here ' off the rails/ Those for 
whom I speak do not deny Activity. They say that psychology 
as a branch of science seeks only to render an account of the 
progressive organization of mind in terms of such mental re- 
lations as we find within our own first-hand experience or 
may be led on the evidence to impute to others. It is not 
concerned with such Activity as may be perhaps must be 
invoked to account for this and all other modes of organiza- 
tion. That lies beyond the strictly limited scope of scientific 

Where we differ is that you include this Beyond under 
' science ' whereas I exclude it. You may ask on what grounds 
I exclude it. In brief, on historical grounds. During the 
seventeenth, eighteenth, and nineteenth centuries the word 
' science ' gradually acquired a well-recognized meaning. The 
man of science professed to render a ' natural ' account in 
due course an ' evolutionary ' account of all that happens. 
That and no more than that was his aim. There were, how- 
ever, other folk than science folk. There were poets, his- 
torians, artists, philosophers, and upholders of religion. They 
sang, taught, and preached creative Activity that lies Beyond 
the purview of science. 

Here were rival claims on the plain man's allegiance. And 


the plain man assigned these claims to science on the one 
hand; to art, morality, and religion on the other hand. Since 
religion often lay nearest to his heart, he put that in the fore- 
front, and emphasized an antithesis between science, with 
its natural worldliness, and religion with its spiritual other- 
worldliness; between the world of science and a realm Be- 
yond science. Hence he was faced by the question : Which 
is it to be, religion or science? He may have decided for one 
or the other; perhaps for one on Sundays, the other on week- 
days. Or he may have said to himself : Why not both all the 
year round? But if both, on what understanding? Perhaps 
he sought counsel from others? 

On the one hand he might be advised to include Activity 
in science; in other words to annul the distinction which for 
so long was regarded as that which earmarked science, as 
such. He finds, however, that many men of science do ex- 
clude Activity as beyond their province of inquiry. For them 
such words as * Force ' (in the mediaeval sense), ' Elan vital/ 
'Entelechy/ have no place in the scientific vocabulary. He 
finds, too, that many poets, historians, artists, and moralists 
and most upholders of religion do include much that 
they regard as Beyond science. And he may believe that the 
distinction which both parties draw is a valid and helpful 
distinction. So he asks: Is there no other way out of the 
difficulty? and seeks further advice. 

Then some may bid him regard all science as deliberately 
and professedly abstract in its aim. Each science selects cer- 
tain relational factors and concentrates inquiry on them. 
The aim of each say in physics and in psychology respec- 
tively is a limited and circumscribed aim so long as each 
keeps to that kind of relations which he has chosen as his 
specialized field of intensive culture. And what is that aim 
alike in the case of the physicist and of the psychologist? 
First, in singular regard, to render an account of all that 
happens within this or that closed system, as such, in terms 
of broad generalizations in large measure statistical in their 
nature. Secondly, in double regard, so to compare results as 
to consider, in joint session, how far the conclusions which 


are reached by the physicist in his closed system can be 
'squared' or 'co-related' with those which are reached by 
the psychologist in his closed system. 

On these terms, if the squaring be such that each party 
can say : Given this in your closed system I can infer that in 
mine; neither goes beyond science, though each goes outside 
his special province of scientific inquiry. 

Each may then say : It seems that between us we cover 
the whole field that lies open to serious inquiry. What call 
is there for either of us, or anyone else, to go Beyond science? 

The question then arises: What, if anything, does lie 
beyond science? 

One traditional reply is : That which lies beyond science 
is the whole realm of art. 

It may then be said that interesting chapters in general 
literature deal with the historical development of artistic 
ideas and their varied expression in creative art-production. 
They are chapters which elucidate certain upper reaches of 
human endeavour where very highly elaborated aims are ' in 
mind/ But they are concerned also with delicate nuances of 
perception, with differentiated space-time ideas, and with the 
deeper-lying sensory endowment which lies near the founda- 
tions of mind ! Above all, the emphasis falls on peculiar and 
specialized modes of appreciative awareness which are felt 
by the artist within his first-hand experience. 

All this affords data for consideration within the province 
of psychology. It may be asked, for example, whether the 
peculiar mental attitudes of appreciation in the mind of the 
artist are in being only at the reflective level of mental 
development. A difficult question for introspection and im- 
putation is thus opened up. And though one may so analyze 
the mental situation as to disclose many factors, it still re- 
mains possible, perhaps probable, that in combining to form 
new wholes they do not of themselves tell the whole secret, 
since, as wholes, these attitudes may have nuances which 
could not be deduced from those of the factors taken severally. 

Many psychological questions in connection with the 
mental procedure of the artist arise. But in so far as the 


treatment is psychological, stress must still be laid on the 
development of artistic ideas, aims, attitudes, behaviour- 
awareness in execution, joy in attainment. Beyond his closed 
system of feelings and ideas the psychologist as such does 
not pass. 

Is this good enough? The artist proclaims that it is not 
good enough. What the psychologist with all his probings 
and searchings fails to discover is that creative Activity, 
operative in him or through him, of which the art-product 
is the visible or audible expression. The art-product itself 
lies open to inspection; the process of art-production may be 
observed; the feelings and ideas in passage through the mind 
may be imputed by one who is himself in some measure an 
artist. But the creative elan of the artist as agent escapes the 
net of scientific generalizations. This lies beyond science; 
and it is in terms of this that one must seek to account for 
not merely to render an account of what happens. 

Akin to art, but with felt difference of attitude in appro- 
bation, is morality. Here, too, the conduct of men lies open 
to inspection. Its genetic affiliation to the behaviour of 
animals may be traced by careful observation of overt acts. 
The psychologist deals with current sense-ideas; with objec- 
tives, unreflective or reflective; with the aims to be attained 
through action; with joy in their attainment; with aware- 
ness in behaving during action; with the mental attitudes 
which have that peculiar 'flavour' we name 'moral/ The 
historical development of moral ideas with liberal diffusion 
of correlative feeling may be set forth at large. Abundant 
data for consideration within the province of psychology are 

And yet this does not touch that which raises the man 
to the status of an agent. Here is directive Activity which 
lies beyond science. And here though not only here there 
is emphasized that insistent claim for freedom which shall 
express the individual uniqueness of the agent in contrast 
with the merely statistical net results with which science so 
largely deals. 

The keynote of that which lies beyond science in art or 



in morality is Activity on the part of some human Agent. 
The keynote of that which lies beyond science in religion 
is Activity on the part of some agent who is regarded as 
Divine. Here, too, all religious ideas, the sublime ends in 
view to be attained, the distinctively religious attitude with 
its 'sweet savour of sanctity/ the joy in participating in 
Activity regarded as more than human; all this falls for con- 
sideration by the psychologist even if it be only, in his 
opinion, a tissue of dramatized fiction. 

The psychologist as man of science claims that in art, in 
morality, in religion, there has been, alike in the race and 
in each individual, advancing development of ideas and 
correlative nuances of feeling. He seeks to tell its story in 
terms, let us say, of evolutionary organization. If he keeps 
within his restricted province of inquiry it is not for him to 
account for this progressive organization of which he renders 
a generalized account. That lies Beyond science. 

In brief, the man of science, as such, is concerned only 
with the evolutionary advance of organization. The philo- 
sopher is chiefly concerned with the creative Activity of 
which this is the expression. If the man of science claims 
that the evolutionary process is universal, the philosopher 
urges that no less universal is creative and directive Activity. 
Neither is antithetical to the other. Each is complementary 
to the other. If the goal of science is to render an account 
of such organization, physical and mental, as is disclosed 
under diligent inquiry, it still remains open to the philoso- 
pher to postulate an organizing Activity, one and indivisible, 
universal and in some sense eternal. This it is that lies 
Beyond science. 

When the physicist has said his last word on the organiza- 
tion of events within his closed system; when the psycholo- 
gist has said his last word on the organization of mental 
occurrences; when in council together they have said their 
last word on such co-relations as may obtain between mental 
occurrences and highly specialized events in the living body; 
the philosopher wants something more. We are told, he says, 
much of what happens; we are told much of the relational 


'how' of what happens. But we are told nothing of the 
creative and directive Activity in terms of which we would 
*ain account for all this. If such there be it lies Beyond 

If there be some universally directive Activity that organ- 
izes all physical events and all mental occurrences in such 
close inter-relation as led to the old-world notion of 'pre- 
established harmony/ the question does not arise whether 
there is 'interaction/ 'interference/ or 'control/ one-sided 
or reciprocal, between physical events and mental occur- 
rences. For if all physical events and all mental occurrences 
are, on all the occasions of their co-relation, the ' expression ' 
or ' manifestation ' of universal Activity, the concept of inter- 
ference or interaction is superseded when we pass Beyond 

But if the Activity that organizes lies beyond science, say, 
as a philosophical ' postulate/ can the psychologist, as such, 
tell us anything about it? Clearly not, so long as he keeps 
within his closed system of ideas. 

It is no doubt very difficult to decide whether introspec- 
tion does, or does not, disclose directive activity within 
first-hand experience. Some find it and some do not. Let us 
assume that not only the idea of activity which of course 
everyone finds but that which this idea ' symbolizes ' may 
be found at the reflective level of mental development as 
part of and one with the ego of mediaeval thought; still this 
falls far short of that directive activity which is conceived as 
the organizing source of all that the man of science is con- 
tent to accept as exemplifying a bewildering number of 
modes of relational organization. There is still a wide range 
of the philosophical realm which lies beyond the reach of 

Into this realm, even in philosophical regard, still less in 
more intimate religious regard, one cannot here enter. The 
point for emphasis here is that t;his realm lies Beyond any 
closed system of science, but not beyond reality. 

If then the psychologist in his vocation as man of science 
has occasion again and again to come into contact with those 


who account for art, history, morality, and religion in terms 
of the directive Activity of human agents, or those who ulti- 
mately account for all evolution in terms of the directive 
Activity of an Agent whom they speak of as divine, he raises 
no protest nay, he may be ready to accept and endorse 
their belief; but not as man of science. As man of science he 
says : Let us keep to such relational treatment as falls within 
our closed system of psychology. 

Alike in a closed system of physical events and in a closed 
system of mind, the time-problem is crucial. What form 
does it assume if we pass beyond science? 

It is commonly held that the Beyond is in some sense 
eternal. This is sometimes taken to imply unlimited dura- 
tion, without beginning and without end or at any rate 

If, however, by ' eternal' we mean 'timeless/ it is clear 
that no time-problem can arise in reference to the Beyond as 
in this sense eternal. But under the heading of * teleology ' a 
difficult question and divergent answers are introduced into 
the field of discussion. 

We have seen that for the psychologist teleological rela- 
tions are distinctively mental. At the reflective level of 
human development they imply a precedent end in view. 
At the perceptive level the mental relations which are their 
predecessors imply at least fore-experience that forestalls 
some coming event. We thus deal with process in time. 
There is incipient or more fully developed reference to the 

Is then universal Activity to be regarded as a process in 
time? One here means Activity itself, not the instances or 
occasions of its operation which are, no doubt, spread out in 
temporal and genetic array. 

Those who have been led to believe that all that happens is 
the expression of universal Activity, creative and directive, 
one indivisible and timeless, are clearly precluded from re- 
garding it as itself a process in time. If then they still use 
the word 'teleological' it must be in some different sense. 
In this sense it implies neither prospective reference to the 


future nor retrospective reference to the past. What then 
does it imply? 

May one say, timeless purpose of which all that happens 
in time is the fluent expression? If so, the word 'purpose' 
needs suitable definition as timeless. And if we speak of this 
purpose as ' teleological/ this word needs suitable re-defini- 
tion so framed as not to imply aught that is 'infected by 
time/ such as a precedent end in view or subsequent satis- 
faction in its attainment. 

Science tries to get down to fundamental principles in 
terms of which an account may some day be rendered of all 
that happens, has happened, and will happen, including all 
that those who are ' immersed in time ' label new and un- 
precedented. Such is the goal of scientific endeavour, ob- 
viously unattainable so long as the temporal universe is still 
in the making. 

But natural science knows nothing of timeless purpose. If, 
then, the philosopher seeks to pass Beyond science in an 
endeavour to account for, and not merely to render an ac- 
count of, all that happens, he should preserve the distinction 
between the things temporal of science and Divine Purpose 
as Beyond time and eternal. 



Lecturer in Cultural Evolution, Exeter University College 

SOCIOLOGY is the youngest of the sciences, and there 
are still many who question its right to be considered as 
a science at all. It is but a century since Auguste Comte 
announced the advent of the new science that was to be the 
keystone of the scientific edifice and the crown of man's intel- 
lectual achievement, and though the last hundred years have 
seen a great increase of interest in social questions and an 
enormous production of sociological and semi-sociological 
literature, there is still little prospect of the realization of his 
ideal. In fact, there has been, in some respects, a distinct 
retrogression from the position that had been reached in the 
middle of the last century. Sociology no longer possesses a 
clearly defined programme and method; it has become a 
vague term which covers a variety of separate subjects. 
Sociologists have abandoned the attempt to create a pure 
science of society and have directed themselves to the study 
of practical social problems. 

Sociology seems in danger of becoming a scrap-heap on 
which are thrown any items that cannot otherwise be dis- 
posed. Nor is this the only danger. Even the writers who do 
deal with genuinely sociological problems frequently do so in 
an entirely unscientific way. 

This is most unsatisfactory, not only from the point of view 
of the sociologist, but in relation to the scientific outlook in 
general. The problem of sociology is probably the most vital 
scientific issue of our time, for if we admit the impossibility 
of creating a scientific sociology we are confessing the failure 
of science to comprehend society and human culture. It is 
impossible to create a scientific civilization from outside by 


a development of the material resources and the external 
mechanism of society. There can be no scientific civilization 
without a science of society. You cannot plan the future of a 
society if you have no knowledge of the true nature of the 
society in question. Moreover, at the present day the plans 
of the economists are at the mercy of the policies of the poli- 
ticians, and the politicians themselves are the instruments of 
a public opinion which is swayed by obscure and non-rational 
forces. The statesman who fails to understand these forces is 
a failure, but his failure is often less dangerous to society than 
the success of the "practical politician/' who understands 
how to use these forces for his personal advancement without 
understanding their social significance. 

The crisis of so-called scientific modern civilization is due 
to its combination of an elaborate technical and mechanical 
equipment with an almost complete lack of social direction. 
The societies of the past possessed their own organs of social 
direction and their formal principles of order, which were not 
indeed scientific, but were based on social tradition. Modern 
society has abandoned this social traditionalism in the name 
of rational principles, but it has done little to create the foun- 
dation of scientific sociology that these principles seem to 
demand. Instead of this our social order is still based on the 
political and moral dogmas of the philosophers of the 
eighteenth century. The doctrines of modern democracy are 
not a scientific theory, but a moral and semi-religious creed 
which owes more than we generally realize to the personal 
inspiration of Rousseau and is hardly separable from the 
mystical Deism with which it was originally associated. This 
doctrine is, in reality, much further from scientific sociology 
than was the old Aristotelian political philosophy, which was, 
within its limits, firmly grounded on a basis of observed facts 
and a rational theory of social life and development. More- 
over, the new movements that have arisen in opposition to 
the dominant theories of liberal democracy are also deficient 
in a pure sociological foundation, and are derived either from 
the economic theories of the nineteenth century or from the 
political philosophy of nationalism. 


Thus we are faced by the contrast of a highly specialized 
development of scientific technique in the external conduct 
of life with an almost complete absence of scientific direction 
in regard to the life of society itself. And yet there can be 
no question of the vast resources of social knowledge that 
have been accumulated during the last century and more. 
The modern development of history and anthropology, of 
economics and of the comparative study of religion is hardly 
less remarkable than that of the physical sciences. A new 
world has been opened up to us in the past, and our resources 
for the understanding of human development and its social 
processes have been immeasurably increased. There is no 
a priori reason for excluding all this new knowledge from the 
field of science. It is genuine scientific knowledge as reliable 
and as systematic in its own sphere as that of the physical 
sciences. It is no mere collection of scattered facts and sub- 
jective opinions, but an organized department of knowledge, 
or rather a number of such departments. 

Why, then, need we despair of the science of society when 
the available resources of knowledge are so great and the 
need is so obvious? But the fact is that these conditions, that 
are at first sight so favourable, have actually been a hindrance 
rather than a help to the development of sociology. The 
most successful sciences are those, like physics and mechanics, 
which found their method before they were involved in a 
mass of detailed observation and before there was any ques- 
tion of using them for practical or utilitarian purposes. 

The development of Sociology has followed the opposite 
course and has suffered accordingly. It started with an em- 
barrassing wealth of material and a desire for premature 
practical results, but with no assured method. The besetting 
sin of the sociologist has been the attempt to play the part of 
a social reformer, whether, like Comte, he embarked on 
grandiose schemes for the reconstitution of society or, with 
the modern sociologist, he plunges into the practical work of 
civic reform. 

The early sociologists were great systematizers with a gift 
for generalization that carried them far beyond the limits of 


sociology proper into the deep waters of ethics and meta- 
physics. They improvized a whole philosophy as a basis to 
their real work as sociologists, with the result that they came 
to think more of their philosophy than of sociology itself. 
Thus the efforts of the Encyclopaedists, the St. Simonians and 
the Positivists resulted in the creation of a theory of society 
which was at the same time a philosophy of history, a system 
of moral philosophy and a non-theological substitute for 

This identification of Sociology with philosophy tended to 
bring the whole subject into discredit and caused a consider- 
able body of opinion in the later nineteenth century to 
despair of the scientific possibilities of sociology, and to look 
instead to the new science of anthropology as an alternative. 
It caused sociologists themselves to react against the specula- 
tive tendencies of the earlier sociology, which they con- 
demned as "armchair sociology," and to immerse them- 
selves in detailed statistical and practical enquiries which 
alone seemed to offer a prospect of concrete results. But the 
new movement avoided rather than solved the real problem 
of scientific method, and it often involved a substitution of 
the study of social machinery for that of society itself. Nor 
did it even escape the old danger of abstract philosophical 
generalization. Modern English and American sociology 
remains to a great extent dependent on the old tradition of 
eighteenth-century moral philosophy. In America, especially, 
the ideal of the ethical reconstruction of society tended for a 
long time to dominate sociological thought, and one of the 
leading American sociologists of the last generation even 
went so far on one occasion as to define sociology as " a moral 
philosophy conscious of its task." It is easy to understand 
how, under the existing circumstances, the sociologist was 
forced to look to an ethical ideal for guidance and help. But 
nothing could in fact be further from the ideal of scientific 
sociology and it led merely to the creation of a pragmatic 
system of social ethics that embodied all the impurities and 


confusions of thought that it is the purpose both of 
philosophy and science to eliminate. 

The continental schools of sociology, on the other hand, 
have been far more conscious of the need for a strict defini- 
tion of scientific method and for the delimitation of the 
province of sociology from both that of philosophy and that 
of the other social sciences. Hitherto, however, they 
have not been altogether successful, although they have 
accomplished much valuable work. Their efforts have been 
handicapped by the confusion that has characterized the 
development alike of modern philosophy and that of the 
social sciences. In the case of the latter there has been an 
overlapping, due in part to the riches of the available material, 
in part to uncertainty of method, and also in part to a non- 
scientific rivalry between the different sciences. 

This has been most serious in the case of the two new 
sciences of Sociology and Anthropology, which have been, 
from the beginning, competitors in the same field. They 
started out, like rival prospectors, to establish as large a claim 
as possible in the unoccupied territories of the new world of 
knowledge; and consequently they both occupied far more 
territory than they had the means to develop. Both of them 
take as their motto "Nihil humani alienum esse puto." The 
Sociologist claims all social phenomena as his province, and 
there are few human phenomena that are not social. The 
Anthropologist claims that his science is the science of Man 
and of human development, and consequently includes every- 
thing from human palaeontology to the comparative study 
of religions. 

It is obvious that if these claims are taken at their face 
value, neither science leaves any room for the other, except 
in so far as the sociologist does admit the existence of physical 
anthropology as an independent discipline. We may almost 
say that both sciences deal with the same subject, and that 
they differ only in the manner of their approach. In practice, 
however, a certain modus vivendi has been reached, although 
it is neither logical nor final. The Anthropologist deals with 
primitive man and his society and culture, the Sociologist 


with the more advanced cultures and with the phenomena 
of contemporary social life. The Anthropologist has had 
somewhat the better of the bargain, since his material lends 
itself more easily to objective scientific study, and conse- 
quently he has done as much in recent years for sociological 
studies as the sociologist himself. This is particularly the case 
in America, where anthropologists, such as Kroeber, Wissler, 
Lowie and Goldenwieser, have produced works which are 
admirable introductions to sociological study and are far 
superior in scientific method to the average textbook of 

This superiority is largely due to the fact that, in dealing 
with primitive cultures, the anthropologist is not embarrassed 
by the rival claims of the historian and the archaeologist. 
The archaeologist and the anthropologist co-operate with one 
another in the study of primitive culture, and there is no 
attempt on the part of the one to dispense with the help of 
the other. The case of the sociologist is very different, though 
through no fault of his own. It was hardly to be expected 
that the historian should welcome the co-operation of the 
sociologist, in the same way as the archaeologist and the pre- 
historian have welcomed that of the anthropologist. 

The advent of Sociology found history already in possession 
of an established position and enjoying a well-earned prestige. 
It was regarded, not as a science, but as literature; it was a 
branch of the humanities, and as such must be judged by 
artistic rather than scientific standards. This conception goes 
back in origin to the historiography of the ancient world from 
which our own historical tradition is ultimately derived. To 
the Greeks history was a form of rhetoric and had nothing in 
common with science, which finds its true pattern in mathe- 
matics and geometry. Science is concerned with the universal; 
history with the particular. Science belongs to the world of 
absolute and eternal reality; history to the world of time and 
change. Science is Truth; history is Opinion. In this respect 
every Greek was a Platonist at heart and shared Plato's belief 


that the less a science has to do with facts which are inevit- 
ably subject to perturbation and change, the more perfect it 
is, and the more it immerses itself in the sensible world, the 
less right has it to be considered scientific. Now this ideal, 
stripped of its metaphysical connotations, has been passed 
down by the scholars and scientists of the Renaissance to 
modern times, and has had a profound influence on current 
conceptions of history. Right down to our own days scholars 
have continued to repeat that history is not science, because 
there can be no science of the particular, and history is con- 
cerned with the study of particular events. 

Consequently the historian is driven either to fall back on 
the old literary-rhetorical ideal, which still possesses a dis- 
tinguished champion in Professor Trevelyan at Cambridge, 1 
or to return to the ethical ideal and like Acton to attribute to 
history the office of a moral censor, or, finally, with Croce to 
identify history with philosophical intuition. 2 

But none of these alternatives is really satisfactory to the 
modern historian, and the prevailing tendency is to maintain 
the independence of history at all costs by treating history as 
an end in itself. 

The most distinguished representative of this tendency 
was the late Eduard Meyer. 3 His attitude to history was, in- 
deed, that of the scientist rather than the man of letters, and 
has nothing in common with the literary-rhetorical ideal. But 
on the other hand he maintains the absolute dissimilarity of 
history from the other social sciences, and bases its claim to 
independence precisely on the old argument of its particular 
and individual character. Sociology and anthropology seek, 
no less than the sciences of nature, to submit human develop- 
ment to general laws and to order the multiplicity of social 
facts according to universal concepts. But in history there is 
no room for general laws or causal principles; its world is the 
world of chance and free human actions, and it cannot pass 

1 Clio, a Muse. 

2 Theory and History of Historiography, Eng. trans. 1921. 

3 See the Introduction to the third edition of his History of 
Antiquity (1910), especially ch. iii. 


beyond this. That is why, he says, "the modern attempts to 
transform the essence of history, and to set before it other 
and * higher' tasks, leave the historian unmoved: history 
exists once for all, such as it is, and will always maintain itself 
in this form, and the business of the historian is with things 
as they are and not with abstract theories. Whether history 
is valued more or less is a matter of no concern to him." 

But in reality, as J. B. Bury has pointed out, it is impossible 
to dismiss the question of the significance of history as a 
matter of no importance. If history has no end except the 
collection of facts for their own sake, it becomes merely an 
intellectual pastime, like stamp collecting. If it is to receive 
the respect that it has always claimed, it must mean some- 
thing in terms of reason and have some relation to the social 
sciences. The fact is that this opposition of history and 
science ignores the whole change that has passed over the 
world of knowledge since modern science and modern history 
made their appearance. Modern science does not aim, like 
that of the Greeks, at the contemplation of unchanging 
truth. It is essentially inductive and experimental, and sur- 
veys the whole world of nature as it lives and moves. It is 
not satisfied with the establishment of a few abstract laws; it 
seeks to know all the facts about the world and to control the 
forces of nature. Moreover, it has been profoundly affected 
by the development of modern biology and the influence of 
the concept of evolution. The new sciences of living matter 
such as botany and zoology, and even non-biological sciences 
like astronomy and geology, are profoundly historical in 
spirit. They do not contemplate a static universe, but an 
evolving process in which the time factor is of primary im- 

And, on the other hand, modern history is no longer satis- 
fied with rhetorical narrative or moral criticism. It seeks to 
understand the past rather as an organic process than as a 
mosaic of isolated facts. It tends to pay less attention than in 
the past to the superficial activity of politicians and diploma- 
tists and more to the action of the permanent social and 
economic forces that determine the life of peoples. Above all, 


it is coming to accept the new concept of Culture which has 
been brought into currency by the anthropologists. It recog- 
nizes that the state is not, as the nineteenth-century historians 
believed, the ultimate social unit and the final end of his- 
torical study. The cultural unity is both wider and deeper 
than that of the state. It is not an intellectual abstraction or 
a by-product of the political process. It is itself the funda- 
mental social reality on which all the other social phenomena 
are dependent. 

History is, in fact, whether consciously or unconsciously, 
becoming the science of social development; not merely the 
science of the past, but the science of the whole human 
culture-process in so far as it can be studied by documentary 
evidence. Thus the old opposition between science and 
history is being done away and history is being brought into 
increasingly intimate relations with the other social sciences, 
and above all with sociology. History and sociology are, in 
fact, indispensable to one another. History without sociology 
is " literary " and unscientific, while sociology without history 
is apt to become mere abstract theorizing.. Hitherto the 
greatest weakness of sociology has been its indifference to the 
facts of history. It has tended to manufacture a history of 
its own which will be the obedient servant of any theory it 
happens to propound. It is hardly possible to open a modern 
sociological treatise without coming across historical " facts " 
that are unknown to the historians and dogmatic solutions of 
historical problems which the historians themselves approach 
with the utmost diffidence. 

This is the inevitable result of the mutual distrust between 
history and sociology and the attempt of each of them to 
assert its own independence and self-sufficiency. In reality 
sociology and history are two complementary parts of a single 
science the science of social life. They differ, not in their 
subject matter, but in their method, one attempting a general 
systematic analysis of the social process, while the other gives 
a genetic description of the same process in detail. In other 
words, sociology deals with the structure of society, and 
history with its evolution, so that they aire related tcf one 


another in the same way as general biology is related to the 
study of organic evolution; neither can attain its end without 
the help of the other. Thus a sociological study of Greek 
culture would concern itself primarily with the organic struc- 
ture of Greek society with the city state and its organiza- 
tion, the Greek family and its economic foundation, the 
functional differentiation of Greek society, the place of 
Slavery in the social order, and so forth; but all these elements 
must be studied genetically and in relation to the general 
development of Greek culture on the basis of the material 
provided by the historian; while the latter, on his side, re- 
quires the help of the social analysis of the sociologist in 
order to interpret the facts that he discovers and to relate 
them to the organic whole of Greek culture, which is the final 
object of his study. It is for the sociologist to define the form 
of a culture and for the historian to describe its content. 

Actually, however, the sociologists have accomplished very 
little in this direction. As we have seen, the discovery and the 
systematic analysis of the cultural unit has been due to the 
work of the anthropologists rather than of the sociologists. 
The latter have been apt to despise such comparatively 
modest tasks and have aimed at something much more am- 
bitious. From the beginning Sociology has been haunted by 
the dream of explaining social phenomena by the mathe- 
matical and quantitative methods of the physical sciences and 
thus creating a science of society which will be completely 
mechanistic and determinist. The path of sociology is strewn 
with the corpses of defunct systems of "social physics," 
" social energetics " and " social mechanics/' and their failure 
does little to discourage fresh adventures. Such systems have 
little use for history or for social reality; they content them- 
selves with generalizations that have no significance and with 
"laws" which are nothing but false analogies. Thus one 
writer maintains that social association is a variety of " the 
law of molecular gravitation " (Carey), another that culture 
is nothing but an apparatus for the transformation of solar 


energy into human energy (Carver and Ostwald), while 
Wimarsky argued that social change proceeds according to 
the laws of thermodynamics. Such extravagances explain 
the distrust shown towards sociology by the historians, for 
their experience of the complex reality of the social process 
makes them naturally hostile to the crude simplicity of 
pseudo-scientific generalizations. 

Yet, on the other hand, it is equally impossible to under- 
stand the life of man and society without the help of the 
natural sciences. In a thousand ways human life is con- 
ditioned and determined by material factors, and there is a 
legitimate materialism which consists in the definition and 
analysis of these relations. History by itself is not enough, 
for it is impossible to understand a society or a culture in 
purely historical terms. Underlying the historical process and 
the higher activities of civilized life there are the primary 
relations of a society to its natural environment and its func- 
tional adaptation to economic ends. The sociologist has to 
study not only the inter-social relations of man with man, but 
also that primary relation of human life to its natural en- 
vironment which is the root and beginning of all culture. 
Here sociology approaches the standpoint of the natural 
sciences and comes closer to the biologist than to the his- 
torian, for the study of a society in its mutual relation with 
its geographical environment and its economic activity has a 
real analogy with the biologist's study of an organism in 
relation to its environment and its function. 

The application of this " biological " method to the phe- 
nomena of society was the work of Frederick Leplay, who 
more than any other sociologist may be regarded as the dis- 
coverer of a scientific method of social study. In this respect 
he compares very favourably with his more famous contem- 
poraries such as Marx, Spencer and Buckle. He succeeded 
in giving an economic interpretation of society which avoids 
the one-sided determinism of the Marxian hypothesis; he 
showed the influence of geographical factors in social life in 
a far more exact and scientific way than Buckle or Ratzel, 
and he provided a biological interpretation of society which 



had nothing in common with the semi-scientific, semi- 
philosophical generalizations of writers such as Herbert 
Spencer. Leplay took as his unit the study of the family in 
its concrete geographical and economic circumstances and 
analyzed its social life and structure in terms of Place and 
Work. His great work, Les Ouvriers Europeens, which 
appeared in 1855, contains a detailed study of thirty-six 
typical workers' families chosen from every part of Europe 
from Eastern Russia to the North of England and from every 
stage of culture from the Tartar herdsmen of the Steppes to 
the artisans and factory workers of Western Europe. 1 He 
studied these, not at second hand, through statistics and blue- 
books, but by the direct observation of their way of life and 
by a meticulous study of their family budgets, which he used 
as a basis for the quantitative analysis of the facts of family 
life. Leplay's method of social analysis affords an insight 
into just those fundamental social realities which so often 
escape the notice of the historian and the student of politics; 
but though it provides a genuinely scientific method for the 
study of society, it is not an exhaustive one. It required to be 
completed by a similar study and analysis of the other social 
units besides the family the rural community, the city with 
its region, and the people and the State, and finally by an 
historical analysis of the social development and the cultural 
traditions of the society as a whole. Owing to his concentra- 
tion on the family, Leplay and his school tended to over- 
estimate the importance of the economic and geographical 
factors and to neglect the contribution of history. Not that 
Leplay was in any sense a materialist. He avoided the pitfall 
of naturalistic determinism which has been the downfall of 
so many sociologists, and fully realized the importance and 
the autonomous character of the moral and religious element 
in social life. But he conceived this in a static form, as an 
invariable which governs social life from outside without 
entering into it. 

1 These were a selection from the 300 monographs that he had 
actually prepared. 


But a culture is not merely a community of work and a 
community of place; it is also, and above all, a community of 
thought, and it is seen and known best in its higher spiritual 
activities, to which alone the name of Culture was first 
applied. It is impossible to understand or explain society by 
its material factors alone without considering the religious, 
intellectual and artistic influences which determine the form 
of its inner cultural life. 

Even if we consider society in its simplest form the family 
we still find these factors intervening in a decisive way. 
Not only do the religious and moral beliefs of a society always 
affect the structure and life of the family, but in some cases, 
as in China and in classical antiquity, the family was itself a 
religious unit and its whole life was consecrated by religious 
rites and based on religious sanctions. 

It may be said that it is not the business of a sociologist 
to concern himself with religious beliefs or philosophical 
theories or literary and artistic traditions, since they he out- 
side his province and are incapable of scientific definition or 
quantitative analysis; yet, on the other hand, it seems absurd 
for him to study the pnysical environment of a society and to 
neglect the spiritual forces that condition its psychic life. The 
primary task of sociology is, no doubt, the study of the social 
structure, but this structure, on the one hand, rests on the 
material foundation of geographical environment and eco- 
nomic function, and, on the other, is itself the foundation of 
a spiritual superstructure which embodies the higher cultural 
values. If we isolate society from its material body and its 
cultural soul, we have nothing left but an abstraction. To see 
the Greek city, for example, in its social reality we must view 
it at once as a product of the earth and as an embodiment 
of Hellenism, like Erechtheus, the hero-king of Athens, who 
was the child of the Earth Goddess and the foster-son of 
Pallas Athene. 

The intrusion of these qualitatively distinct categories or 
orders of being into the sociological field is a great stumbling- 
block in the social sciences. The natural scientist has a com- 
pletely homogeneous material in the material phenomena 


that he investigates; so also has the philosopher in the region 
of ideas; but the sociologist has to deal impartially with 
material and spiritual factors, with things and ideas, with 
moral and economic values, with all the multifarious ex- 
perience of the two-sided nature of man. 

Sociologists have always been conscious of this problem, 
and the spectacle of the brilliant results attained by physical 
science in its uniform field of study has often tempted them 
to find a way out of their difficulties by an arbitrary or one- 
sided simplification of their data. There is something very 
attractive about a " simple " explanation of the social process 
which treats the relation of the different factors as one of 
simple causal dependence and regards one of them as abso- 
lute and the rest as secondary derivations from it. 

The most popular type of " simple " explanation is, of 
course, the materialist one, which attempts to deduce the 
whole social process from economic or geographical or racial 
factors, and relegates the cultural superstructure to a lower 
plane of reality as a subjective reflection of material con- 
ditions. The classical example of this is the Marxian theory, 
which reduces both history and society to their economic 
elements and regards the spiritual element in culture as 
secondary and derivative. In the words of Marx, " the mode 
of production in material life determines the character of the 
social, political and spiritual processes of life. It is not the 
consciousness of men that determines their existence, but 
their existence that determines their consciousness . . . with 
the change of the economic foundation the entire immense 
superstructure is more or less rapidly transformed." 1 

Now the error of this method of interpretation does not 
consist in the view that the ideological aspects of culture have 
a material basis in the economic life of society, but in the 
assertion of an absolute causal dependence which denies the 
independent significance of the spiritual factor in society. On 
the one hand, the concept of culture is arbitrarily impover- 
ished by being emptied of all the values that are not explic- 
able in economic terms, and on the other the economic 
1 Zur Kritik der Politischen Oekonomie. Intr. 


category is arbitrarily expanded in order to include a whole 
series of non-economic elements. 

This fallacy is not peculiar to the Marxists; we find it 
equally in the theories that profess to explain the whole 
development of culture on racial grounds and which use the 
Aryan race or the Nordic type as the deus ex machina of the 
historical process. Such theories explain everything, but also 
they explain nothing; they are like the conjuror's hat, which 
is equally capable of producing a cabbage or a white rabbit, 
as the occasion demands. 

At the opposite pole to these materialistic simplifications is 
the idealist simplification which deduces the social process 
from the spiritual element in culture. To Hegel and his 
followers History is the progressive self-manifestation of 
absolute Mind. Each culture or people is a successive proposi- 
tion in the process of a cosmic dialectic, and the material 
aspects of culture are merely the embodiment of the imma- 
nent idea. Such theories are now almost entirely discredited; 
nevertheless, we must remember that they played an essential 
part in the development of their apparent opposite the dia- 
lectical materialism of Marx. Moreover, although the his- 
torical panlogism of the Hegelians is looked on by sociolo- 
gists today merely as an historical curiosity, its elder rival, 
the rationalist idealism of the Liberal Enlightenment, still 
preserves its prestige in spite of all the ridicule and argument 
that have been directed against it from the time of Burke and 
de Maistre to our own days. This Liberal idealism is marked 
by a belief in an absolute Law of Progress and an unlimited 
faith in the power of reason to transform society. Concepts 
such as Liberty, Science, Reason and Justice are conceived, 
not as abstract ideas, but as real forces which determine the 
movement of culture, and social progress itself, instead of 
being regarded as a phenomenon that requires explanation, 
is treated as itself the efficient cause of social change. Beliefs 
of this kind are religious rather than sociological, as Pareto 
has shown in the incisive criticism of his Trattato di socio- 
logia generate. Nevertheless, they still exercise a powerful 
influence on popular sociology, and they are not altogether 


absent from the theories of such distinguished modern writers 
as the late Professors L. T. Hobhouse and Lester Ward, 

There remains yet a third type of explanation, which seems 
at first sight to offer a more satisfactory way of approach than 
either the materialistic or the idealist theories, since it pro- 
fesses to explain social phenomena in purely social terms. 
Nevertheless, this " sociologism " suffers from precisely the 
same defect as the other " simple " theories. For if, on the one 
hand, we attempt to study social relations apart from their 
material foundations and their cultural value, as the 
" formal " school of sociologists represented by Simmel and 
Von Wiese wish to do, we empty sociology of its content and 
are left with a series of logical abstractions. If, on the other 
hand, we reduce both the material and the spiritual element 
in culture to purely social sources, we are guilty of just the 
same unscientific simplification as the adherents of economic 
determinism or Hegelian panlogism. No doubt the exponents 
of this theory, such as Emile Durkheim, give a much wider 
analysis of the spiritual element in culture than do the 
materialists, and, in particular, they do full justice to the im- 
portance of the social function of religion, but they do this 
only by hypostatizing society into an independent spiritual 
power : not only is the social the cause of the religious, but 
the two are identical, and the Divine is the social sublimated 
to an ideal plane. This is not a scientific explanation, but an 
amalgamation of religion and society by means of an illegiti- 
mate substitution of one category for another. 

The fact is that all "simple" explanations are unsatis- 
factory and irreconcilable with scientific sociology. It is im- 
possible either to make society its own cause or to deduce 
social phenomena exclusively from material or spiritual ones. 
As Pareto has shown, the essential requirement of sociological 
method is to abandon the idea of a one-sided relation of 
causal dependence between the different factors and view the 
social process as the result of a complex series of interdepen- 


dent factors. Material environment, social organization and 
spiritual culture all help to condition social phenomena, and 
we cannot explain the social process by one of them alone, 
and still less explain one of the three as the cause and origin 
of the other two. 

Although the sociologist must take account of the geo- 
graphical, economic and intellectual or religious conditions 
of a social culture, he has no more right to lay down the law 
on philosophy or theology than on geography or economics. 
But though this is generally recognized in the case of the 
science of nature and even the other social sciences, sociology 
has been far less scrupulous in dealing with the sphere of the 
higher spiritual values. It is often argued that these are a 
product of the social process, since there can be no spiritual 
culture apart from society, and therefore " spiritual sciences " 
(Geisteswissenschaften) can claim no scientific autonomy. 

This, however, is the result of a naive confusion of thought. 
All the spiritual activities that appear in culture religion, 
philosophy and science possess their own formal principle. 
They are not mere functions of society, but have their own 
ends, which in a real sense transcend the social category. The 
sociologist, no doubt, is justified in studying a religious belief 
in its influence on society, but the theologian does not judge 
his belief or theory in terms of social value, but in terms of 
religious truth. 

So, too, with scientific ideas; Durkheim has given a most 
ingenious exposition of the way in which man's ideas of time 
and space have a subjective basis in the rhythm and order of 
social life. But the scientist himself aims at transcending all 
such social subjectivism and attaining some absolutely objec- 
tive standard of measurement. In other words, the more 
" anthropomorphic " a scientific idea is, the more interesting 
it is to the sociologist and the more worthless it is to the prac- 
titioner of the particular science in question. 

Actually, however, there is little danger at least, outside 
Russia of the Sociologist dictating to the naturalist or 
attempting to " sociologize " science as a whole. But there 
is, as we have seen, a real danger of the sociologist trespass- 


ing on the territory of the other Geisteswissenschaften and 
attempting to play the part of a theologian or a philosopher. 

A sociologist is, of course, quite within his rights in arguing 
that religion is necessary to society, or the reverse, or that a 
particular religion is beneficial or harmful to a particular 
society. For example, he might conclude from the study of 
ancient civilization that the introduction of Christianity was 
fatal to the institutions of the city state and the tradition of 
Hellenic culture. But this would not justify him in drawing 
conclusions about paganism or Christianity qua religion. 
That is a matter for the theologian. 

When Professor Ellwood, in his well-known book The 
Reconstruction of Religion, argues that religion is necessary 
to society and performs important social functions, he is 
reasoning as a sociologist, but when he goes on to "recon- 
struct" religion and to propound a new form of socialized 
Christianity, he is exchanging the role of a sociologist for 
that of a theologian. 

It is no matter whether the religious theories that we 
propound are materialist or supernaturalist, rationalist or 
mystical, theistic or humanitarian. The point is that when 
we once begin to make a religion or to discuss purely religious 
values, we enter the theological region and speak as theo- 
logians, not as sociologists. 

Even since the time of Comte there has been a constant 
succession of theological sociologies which aim, not at the 
study of actual societies or actual social phenomena, but at 
the reformation of society on the basis of a new religious 
ideal. These attempts have been almost uniformly unsuccess- 
ful, for they are vitiated by an inherent confusion of method. 
They try to produce a synthesis between religion and soci- 
ology, and they succeed only in creating a hybrid monstrosity 
that is equally obnoxious to scientific sociology and to genuine 
religious thought. 

I do not say that it is impossible for a sociologist-philo- 
sopher-king to plan the organization of society deliberately 
on the basis of general philosophical principles. Something 
of the kind was, indeed, accomplished by the Tokugawa 


Shoguns, who gave Japanese culture a conscious unity like 
that of a work of art. But they could appeal to the prestige of 
the Confucian tradition that is to say, to an inspired soci- 
ology that had a genuine religion and a divinized sage behind 
it. If lyeyasu had manufactured a new religion of his own to 
meet a purely social need, it is very unlikely that he would 
have been as successful as he was. 

The sociologist who creates a religion of his own for socio- 
logical purposes is just as unscientific as if he were to invent 
new anthropological or geographical facts to suit his theories. 

As sociologists we have to accept the existence of this inde- 
pendent order of spiritual truths and values and to study their 
influence on social action. Whether society requires a re- 
ligious foundation; what is the actual working religion of our 
particular society; how far material and social factors affect 
religious beliefs and philosophical points of view; all these 
are questions for our study. But the objective intellectual 
validity or spiritual value of religious doctrines and philo- 
sophical theories lies entirely outside our province. 

It does not, of course, follow that these questions are in 
themselves insoluble or otiose. There is no reason for the 
sociologist who observes the limits of his science to write off 
everything beyond it as unreal or as matters of arbitrary 
speculation. No doubt the study of social phenomena in their 
complex irrationality has often led sociologists to prefer the 
despairing scepticism of a Macchiavelli or a Pareto to the 
self-confident dogmatism of the idealists. Nevertheless, if 
such an attitude is justifiable it must be justified on philo- 
sophical grounds. The sociologist as such does not possess 
the necessary data for making a universal judgment of this 
kind. Here again he must follow the example of the historian, 
who no longer seeks to use history in order to justify his 
political or religious opinions, but who seeks to understand 
the beliefs of the past as a means to understanding its history. 

This method of sociological analysis can be applied to 
practically every social phenomenon, even to those which 
seem at nrst sight to be entirely non-spiritual in character. 
For example, Max Weber, one of the first modern exponents 


of " a sociology that understands " (verstehende Soziologie), 
has shown how the development of Capitalism is not to be 
explained as a purely economic process, but has its spiritual 
roots in a new religious attitude towards industry and saving 
that grew up in Protestant Europe after the Reformation. 
On the other hand, there are other phenomena which seem 
at first sight to be purely religious and yet have their basis in 
economic or social causes. 

Thus every social type or institution is the result of the 
complex interaction of a number of factors that are qualita- 
tively distinct and can never be reduced to simple unity. 
Take for example the social type of the Samurai in Japan, a 
type which seems sociologically simple enough, since it repre- 
sents an obvious social function in Japanese society. Never- 
theless, in order to understand it, it is not enough to study 
the historical evolution of Japanese feudalism and the eco- 
nomic structure of Japanese society. The Samurai type is also 
the embodiment of a whole complex of moral ideas and 
religious beliefs native, Confucian and Buddhist some of 
which have a very remote relation both to Japan and to the 
military tradition. And the ethical code or cultural ideal that 
is the outcome of all this is not merely a matter of historical 
interest; it is an abiding element in the Japanese social tradi- 
tion, and without it it is impossible fully to understand either 
Japanese politics or Japanese thought. 

But if Sociology needs the help of philosophy and theology 
in order to understand the spiritual elements in the social 
process, it also renders services to them in return. We cannot 
understand an idea unless we understand its historical and 
social foundations. We cannot understand the Greek institu- 
tion of citizenship unless we study its spiritual foundations 
in the religion of the city and the family. But on the other 
hand we cannot understand the Greek philosophical ideal of 
political liberty and its ethical ideal of "magnanimity" 
without a knowledge of the political life and the social struc- 
ture of the Greek state. And even our modern ideas of liberty 
and democracy are not unaffected. The philosophers of the 
eighteenth century interpreted the classical ideas of liberty, 


democracy, etc., in an abstract and unsociological way, and 
consequently they misinterpreted them, and this misinterpre- 
tation was not without its influence on their philosophical 

In the same way the theologians have often failed to recog- 
nize the social and economic elements in religious phe- 
nomena, with the result that they have confused religious 
and sociological values and have allowed a racial or economic 
opposition to translate itself into a religious conflict. Most of 
the great schisms and heresies in the history of the Christian 
church have their roots in social or national antipathies, and 
if this had been clearly recognized by the theologians the 
history of Christianity would have been a very different one. 

A scientific method of sociological analysis may serve the 
same purpose for society as a psychic analysis may accom- 
plish for the individual by unveiling the causes of latent 
conflicts and repressions and by making society conscious of 
its real ends and motives of action. The actual tendency of 
practical politics, especially in democratic countries, is un- 
fortunately just the opposite, since they invest such conflicts 
with a halo of idealism and thrive on sociological misunder- 

This is the more regrettable because the modern state is 
daily extending its control over a wider area of social life and 
is taking over functions that were formerly regarded as the 
province of independent social units such as the family and 
the church, or as a sphere for the voluntary activities of 
private individuals. It is not merely that the state is becom- 
ing more centralized, but that society and culture are be- 
coming politicized. In the old days the statesman was re- 
sponsible for the preservation of internal order and the 
defence of the state against its enemies. Today he is called 
on to deal more and more with questions of a purely socio- 
logical character, and he may even be expected to transform 
the whole structure of society and refashion the cultural tra- 
ditions of the people. The abolition of war, the destruction 
of poverty, the control of the birth-rate, the elimination of 
the unfit these are questions which the statesmen of the 


past would no more have dared to meddle with than the 
course of the seasons or the movements of the stars; yet they 
are all vital issues today, and some of them figure on the 
agenda of our political parties. It is obvious that the solution 
of these problems calls for all the resources of sociological 
science even supposing that science was in a much more 
advanced state than it actually is; yet the unfortunate poli- 
tician is expected to provide a solution by his common sense 
enlightened by a cloudy mixture of economic materialism 
and moral idealism. We can hardly wonder at the popularity 
of Marxian Socialism, for that at least has a sociology of a 
kind, though it is elementary and one-sided. 

A sociology which disregards its proper limits may create 
Utopias, but it cannot help the statesman in his practical 
tasks. What we need is a scientific sociology which will trans- 
form the art of politics in the same way that the modern 
sciences of biology and physiology have transformed the art 
of medicine. In the task of restoring spiritual order and social 
health to our distracted civilization sociology has, as Comte 
realized, an essential part to fulfil. But it is to be achieved, 
not by usurping the functions of philosophy and theology, as 
in the Positivist synthesis, nor by ignoring moral and spiritual 
values, as with Marx. It must recognize at once the deter- 
mination of natural conditions and the freedom of spiritual 
forces, and must show how the social process embraces both 
these factors in a vital union like that of the human organism. 

Such a sociology alone can prepare the way for the coming 
of a new applied science of politics which would plan the 
City of Man, not by the rule of abstract ideas and visionary 
theories, nor in terms of material size and wealth, but as a 
true community. 


By the REV. M. C. D'ARCY, S.J. 

Campion Hall, Oxford 

THE history of theology shows that while theologians 
are often distracted from their proper business by 
contemporary scientific opinion, the principles on 
which it rests and the methods appropriate to it are different 
from those of the physical sciences. Science, in the modern 
and confined sense of the word, may be said to date from 
the sixteenth century, and it has been defined as a well- 
criticised body of descriptive knowledge based on observa- 
tion and experiment. The word observation implies that the 
subject matter is visible or of the sort that could be made 
visible, and the word experiment, again, implies that one can 
bring to bear certain methods of investigation and verify 
their success by sensible experience. It took man a long time 
to find out what these methods were; once discovered they 
proved to be a more potent art than that of Prospero to bring 
a mutinous nature to heel. Various reasons, however, among 
which their rapid success must be counted, conjoined to hide 
the fact that they were not suited to all realms of knowledge 
and that their very success was gained through sacrifice. To 
the detriment of philosophy and the dismay of certain 
theologians the truths contained in the old philosophies 
based on Plato and Aristotle and the methods followed by 
them were set aside. Tired with the constant appeals to the 
authority of Aristotle and intoxicated with success men like 
Bacon declared that they would " no longer be kept dancing 
in rings, like persons bewitched, but our range and circuit 
will be as wide as the compass of the world." The coinci- 
dence, therefore, of a decadent scholasticism and a new 
method, which by its initial successes seemed to have the 
world at its feet, brought confusion into the ranks of the 


philosophers and the theologians, and many of the latter, to 
use another image of Bacon, were diverted by science from 
their true course like the runners by the golden apples of 

The effect of this reaction from the old was to bring meta- 
physics into disrepute and to bestow on the mathematical 
sciences the exclusive right to knowledge. That theology was 
involved in the downfall of metaphysics was not fully 
realised for some time. The ultimate consequences of a revo- 
lution usually take time to be assimilated, and so it is not 
surprising to find that the seventeenth century was intensely 
religious and that great physicists like Newton were not 
aware of the conflict between their faith and the marvellous 
mechanical world of their theories. Moreover, many re- 
ligious thinkers consciously or unconsciously in accordance 
with the trend of the period abandoned thought as an aid 
to religion. Faith, this group proclaimed, echoing the words 
of the chief of the Reformers, is an experience, an assurance 
of confidence; "reason is directly opposed to faith, and so 
one should let it go; it should be slain and buried by 
believers." Those, therefore, who regarded the Sorbonne as 
" a damned synagogue of the devil " were not likely to con- 
test in the name of religion and theology the claim of the 
mathematical sciences to be the exclusive proprietors of 
knowledge. And, as if this were not enough, two verdicts of 
distinguished philosophers came to be accepted, despite their 
differences, as the law on the relations of science and 
theology. The first was that of David Hume. His verdict r eHed 
on the evidence of the Cartesian philosophy and the prin- 
ciples professed by contemporary science, and it came to this, 
that if sensation be equivalent to knowledge, then all such 
conceptions as God, substance, and cause must be put aside 
as illusory and we must content ourselves with a world of sen- 
sation and a subject which feels and is like a target dotted 
with experiences. Such a verdict, of course, left no room for 
theology nor even for science, as no meaning could be given 
to inductive method nor any explanation of its success. The 
scientists, however, did not apply the lesson to themselves; 


they saw only that theology had been sentenced to death. It 
needed a second philosopher, Kant, to grasp the extent of the 
damage and revise the verdict of Hume. Science, he main- 
tained, was not an affair of sensation alone, but of a happy 
conjunction of it with thought. Neither sensation nor 
thought by itself could be productive; the former was too 
feeble, while the history of metaphysics showed that thought 
by itself was always sterile. Human nature, being composed 
of mind and body, could not advance in knowledge without 
the aid of both, and so it was well adapted to the understand- 
ing of the visible sensible world and incapable of knowing 
and criticising what lay beyond it. By this means Kant 
justified science at the expense of theology but not of re- 
ligion, as he thought; for he went on to say that if science 
could not find a God, neither could it criticise God if he 
existed, and that he did exist he thought was certain, in 
that he was a necessary postulate for moral experience and 

This olive branch offered by Kant did not bring the lasting 
peace that he had hoped. It tended to obscure still further 
the principles on which theology rested and gave an exag- 
gerated estimate of the mathematical sciences. No longer 
would philosophers use the classical arguments for the exist- 
ence of God, as they were supposed to have been invalidated 
by Kant's criticism of them. Those who refused to accept 
the scientific account of the universe as complete and ex- 
haustive had recourse more and more to some special kind 
of experience which was called religious. It would be impos- 
sible to give a just appreciation of the variety of forms which 
this experience has taken; nor is it altogether necessary, as ex- 
tremist views are now being laid aside and an attempt being 
made to widen the term so as to include what is best in 
thought as well as in feeling. The formulae of Hume and Kant 
are, in fact, undergoing revision at the hands both of the re- 
ligious thinker and the scientist. The latter has indeed con- 
tinually passed beyond the limits laid down by Hume. In 
the nineteenth century men like Huxley and Tyndall were 
stirred by a religious, if anti-theological fervour* They 


wanted a view of life. " There is grandeur," wrote Charles 
Darwin, " in this view of life with its several powers, having 
been originally breathed into a few forces or into one; and 
that, whilst this planet has gone cycling on according to the 
fixed law of gravity, from so simple a beginning endless 
forms most beautiful and most wonderful have been, and 
are being, evolved/' This lure of philosophy has become 
more and more potent with the coming of the revolutionary 
changes in science and the resulting alarums and excursions. 
The physicist in his laboratory may pray to be relieved of 
the spying of reporters and the real or bogus interest of his 
philosopher friends, but in the end he does not resist the 
appeal to say a word at the British Association or talk round 
theology in Gifford lectures. And in the end he can hardly 
do otherwise, for the classical principles of physical science 
have become so involved and so often checkmated by experi- 
ment that the very foundations have come to be questioned. 
Experiment is at loggerheads with observation, and such a 
situation provides a happy hunting ground for the philos- 
opher and theologian. 

I need not insist on this change of front among the 
scientists. It will be enough to point to what is called the 
new principle of indeterminacy and the danger of scientists 
losing their heads and thinking that they have made the 
first and scientific discovery of free will; to the confession of 
theism by J. S. Haldane, of a mathematical or architectural 
source by Jeans, of "one systematic fact, which is the 
antecedent ground conditioning every creative act" by 
Whitehead. These examples could easily be supplemented 
by quotations from the writings of such diverse thinkers as 
Lloyd Morgan, Julian Huxley and Eddington. They are not 
at all agreed as to the means of passing beyond science or 
what God should signify, and few give, as Whitehead does, 
a sustained criticism of the foundations of science and 
attempt to forge a new philosophy out of the criticism. The 
majority, having accepted a naive realism and having 
worked within the framework of the philosophy of Descartes 
and Hume, have been fought to a standstill by nature. In 


the old view, now entirely surrendered, substances were 
thought to move about in space unchanged; it was based on 
observation and assumed that fundamentally the real world 
must be microscopically what ordinary objects were macro- 
scopically, that atoms and electrons were like billiard balls 
and always so. As Eddington says : " the Victorian physicist 
felt that he knew just what he was talking about when he 
used such terms as matter and atoms. Atoms were tiny 
billiard balls, a crisp statement that was supposed to tell you 
all about their nature. . . ." Hence, starting with observa- 
tion, the scientist proceeded to make hypotheses on the like- 
ness of the observed object, omitting, of course, all that was 
irrelevant. A change came about when the hypothesis failed 
to work, and the scientist felt himself forced to picture 
nature structurally as a physico-spatial-temporal real which 
must be treated very severely by means of mathematical 
equations. This meant that he had to start from the micro- 
scopic to the macroscopic and not vice versa, and at the 
present moment it has landed the scientist in agnosticism. 
" Now we realise that science has nothing to say as to the in- 
trinsic nature of the atom. The physical atom is like every- 
thing else in physics, a schedule of pointer readings" 
(Eddington). For the moment, that is, one school of 
scientists has passed a self-denying ordinance. So far as they 
are concerned, as has been remarked by one of them, a 
theory that all changes are due to the influence of demons 
is just as feasible as any other. That scientists do not take 
this hypothesis seriously is, as Einstein has remarked, "a 
question of good taste "; they like neatness, and so " to com- 
prehend signifies a reduction in the number of the axioms." 
We cannot hope to know, or at least have no means of know- 
ing at present, how nature works. All our experiments are 
bound to deform it and in a constantly altered world there 
is no meaning in asking whether the principle of causality 
or uniformity holds true of it. " That it is valid statistically 
experience leaves no doubt, but so are the formulae of the life 
insurance company " (Lindemann). 

Now there must be something in the scientific method 



which is accountable for such conclusions, and I do not 
think that it is far to seek. Bukharin, in his address in 1931 
to the delegates of the U.S.S.R. on the Theory and Practice 
from the Standpoint of Dialectic Materialism, put his finger 
on it. "The crisis in modern physics and equally in the 
whole of natural science, plus the so-called mental sciences 
(Geisteswissenschaften) has raised as an urgent problem, 
and, with renewed violence, the fundamental questions of 
philosophy: the question of the objective reality of the ex- 
ternal world, independent of the subject perceiving it, and 
the question of its cognisability (or, alternatively, non-cog- 
nisability.) Nearly all the schools of philosophy, from the- 
ologising metaphysics to the Avenarian-Machist philosophy 
of ' pure description ' and renovated ' pragmatism/ with the 
exception of dialectical materialism (Marxism), start from 
the thesis, considered irrefutable, that ' I ' have been ' given ' 
only 'my' own "sensations/" As evidence for this state- 
ment he quotes, besides Mach and Avenarius, K. Pearson, 
Bergson, James, Vaihinger, H. Poincare, B. Russell, Ph. 
Frank, M. Schlick and R. Carnap. That this diagnosis is 
right can scarcely be doubted. Einstein, for instance, when 
he tells us that "to understand is to draw one incompre- 
hensible out of another " is relying on the assumption that 
we begin with sensation alone and that what thought does 
is to link together the sensations by means of some descrip- 
tive theory. The same view is very clearly expressed by 
Lindemann. "The primary data which man shares with 
other animals are the experiences we call sense-data. Thanks 
to his memory, each individual can compare such experi- 
ences with previous ones. As civilisation has advanced man- 
kind has been more and more concerned to collect such 
sense-data into a system subsuming the experiences which 
had been undergone and into which each fresh experience 
fitted. Any system capable of fulfilling these conditions is 
satisfactory; which one is preferred can be merely a matter 
of individual taste/' 

What, then, is the position of the theologian in the light 
of the teaching of modern science? All depends on whether 


he accepts or not the claims and presuppositions of that 
science. There are some who are thankful that science is 
now taking up such an agnostic attitude; the mist is no 
longer in the air concealing the heavens, but covering the 
ground. And if this new hope seems to many, including 
myself, precarious, it must be remembered that not only the 
theologian but the scientist also has been glad to avail him- 
self of the present plight of physics to invoke religion. In 
genuine humility some have turned from their so-called fic- 
tions or descriptions to a belief founded on revelation or re- 
ligious experience or mysticism. In the first case, the belief 
takes the form of fideism, a view often taken up in the past 
and quickly dropped because it interferes with the longing 
of a man to think out his origin and destiny. Such a belief 
has given comfort to many, but I think that it must neces- 
sarily be episodic and not permanent, as man cannot for- 
swear for a long time all thought on his origin and destiny, 
even though divine revelation is surrounded, as by a Karl 
Barth, with an atmosphere of apocalypse and prophecy. As 
to experience and mysticism, much depends on what is 
meant by these terms, and one of the hopeful signs of the 
times is the amount of careful study and analysis that has 
been given to them. Owing to the course which religion and 
science have followed since the Reformation, experience has 
unfortunately been assumed to be in some ways irrational or 
super-rational, and this view has had support from philos- 
ophers like James and Bergson. I am sure that this way of 
religion is a cul de sac, and there are welcome signs that this 
is being recognised. Books such as Philosophical Theism by 
Dr. Tennant pay scant attention to the argument from ex- 
perience. Dean Inge and Dr. Matthews are less hard- 
hearted, but they, too, protest against the uncritical accept- 
ance of experience as the one guarantee of religion. After 
all, in no other sphere of human activity or passion are the 
truth and value of the feelings and intuitions and experience 
judged by their evidence alone, and religion can carry no 
conviction to one who wishes to ascertain the grounds of its 
truth, if it relies on such a subjective standard. 


Without deserting the test of experience, some do try to 
make it less subjective. One way is to borrow the scientific 
method of verification. They say that here undoubtedly is 
an experience which cannot be taken into account by 
science. It should not, however, for that reason be dismissed, 
for if we look at its place and history in human life, we see 
that it is responsible for some of the highest values and that 
life would be infinitely poorer were it taken away. It cannot, 
therefore, be false or illusory. It will be noticed that the 
same argument is here being used for religion as has been 
used in the defence of morality and art. A physical world as 
described for us in terms of physics leaves no room for 
quality, for beauty or goodness; man, therefore, must be in 
some other way in contact with them, and it is fair to put 
the religious sense alongside that of the aesthetic and the 
moral. The trouble with this argument is that it still hides 
itself under vague titles, and many have cast doubt on the 
precise object of aesthetics, questioning whether it be wholly 
objective. This difficulty might be overcome if, as Otto has 
maintained in his Das Heilige, it could be shown that man- 
kind possesses a sense of the divine. Valuable as Otto's con- 
tribution is to theology, I do not think that his analysis of 
the Holy and the ' numinous 9 is above criticism, for we are 
left at the end still wondering what precisely is the sense, 
whether it is chiefly emotional or intellectual, and if it is 
intellectual, how God can be said to be apprehended directly. 
Dr. Matthews and others regard this view as an improve- 
ment on that of Schleiermacher, who held that religion is a 
"feeling of absolute dependence/' and Dr. Matthews him- 
self prefers the expression of Boutroux, " the Beyond which 
is within," and looking for some deep and permanent 
needs of the human spirit to explain man's religiousness, 
finds them in "two salient and ineradicable needs of the 
spirit . . . the need for unity and the need for the sub- 
stantiation of value." 

Thus we see that the theologians belonging to the school 
of experience are moving to a sounder position than that 
held formerly when science was suppposed to hold exclusive 


rights over reason and religion was referred to an irrational 
or super-rational experience. It cannot be said, however, 
that they are out of the wood yet, and there is one strange 
assumption which even now remains unquestioned. It sticks 
out in the words of Dr. Matthews when he looks " for some 
deep and permanent needs of the spirit/' Here, we notice, 
need is the criterion, and God and religion are brought into 
court to have their claims settled on the one count, whether 
I want them or not. This brings out the revolutionary 
change in theology which passed almost unnoticed. The 
old theology began with God and then proceeded to argue 
from His nature to what must be the right relation of man 
to such a being, and this it defined as religion; now we begin 
with what we should desire, with religion as a human value, 
and cut a pattern of God to suit our desires. This may be 
a legitimate way of proceeding, and if, of course, we are 
afraid of intellect in religion it may be thought to be the 
only way, but it remains surely a very dangerous one; it sug- 
gests, in fact, that a god, if he exists, may take his import- 
ance from us and be like a sleeping Endymion or impotent 
until we entice him into life by our calls upon him. Acting 
on this belief theologians have made a close study of the 
common motives which lie behind all the various manifesta- 
tions of religion, and I should say that the chief value of 
such work lies in this, that it has taught us much about the 
nature of man; but it is not so clear that it will suffice for an 
understanding of religion. The old method was to take the 
data of any experience and to submit them to the test of 
reason; philosophy was considered to be such a reflection 
and it offered us an enlightened and austere vindication in 
systematised form of all that was given, no matter how, in 
experience. Just as in science, physical or biological, medi- 
cal or psychical, the data cannot be taken at their face 
value but must be sifted and approved of by reason, with the 
help of inductive or deductive methods, so in religion, save 
that theology might have to rely more on deduction than 
on observation and experiment. The disinclination to 
follow this way can be traced back to the rift made in the 


past between reason and faith (of which I have already 
spoken) and the anxiety of so many theologians to remove 
religion from the embrace of that mechanical determinist 
philosophy which dominated Europe for a while and was 
supposed to be the supreme work of the human mind. 

The time seems now to have come when both the 
scientist and the theologian are beginning to talk a similar 
language instead of looking at each other from a distance. 
The theologian is, as I have explained, deserting the ground 
of mere experience and not only has science forsworn its 
pretensions to an exclusive knowledge of reality, but it is in 
danger of moving too far in the opposite direction. The 
most promising sign is not the scepticism of a Lord Russell, 
nor the overturning of the tables of science and philosophy 
alike by a Wittgenstein, nor even the tentative efforts at a 
theology made by Sir James Jeans, but the thorough over- 
hauling of scientific presuppositions by Whitehead. The 
difference between these two latter is that Jeans still takes 
as the standard of all thinking about reality mathematics 
and not metaphysics, and so permits only a God who can be 
addressed in mathematical terms, whereas Whitehead, hav- 
ing demolished this assumption of Jeans', is able to go ahead 
with a new philosophy of nature and a much more compre- 
hensive account of God. This, I think, is a vital difference, 
as great, in fact, as that which divided Plato with his intel- 
ligible world from the atomists, and one, too, which gives 
scope for a theology properly so-called. 

The line of thought newly opened up by Whitehead is 
one which was followed by the older tradition of theology, 
and it matters little whether one agrees with his conclusions 
or not so long as the significance of his point of view be 
grasped. The great successes gained by the introduction of 
the mathematical methods at the Renaissance concealed the 
fact that that victory was gained at a price. Impera indeed 
but divide, and this division meant the choice of an abstrac- 
tion, the sacrifice of the hope of knowing the world wholly 
and intuitively. Even so, all might have gone well if the 
nature of this sacrifice had been kept in mind, but success 


suggested contrast with slow-moving metaphysics, and the 
philosophers themselves fell under the spell of science. Hence 
it was laid down that our knowledge was confined to the 
sensible world, "that the primary data which man shares 
with other animals are the expenences we call sense-data." 
There are two mistakes here which are closely allied. Begin- 
ning with observation man is aware of a sensible something, 
a thing possessing extension and colour at least; but the 
secret of the success of man as a scientist was to ignore the 
thing and the quality of it and to concentrate exclusively 
on the one part of the object which was calculable and so 
reducible to " a system of measurable relations between 
countable x's." What was left over was first ignored and 
then in time came to be regarded as not falling within know- 
ledge. Thus the first mistake arose, and the second was a 
corollary of the first, consisting in the erroneous idea that we 
knew only our sensations. Thus it came about that with 
one fell stroke the supreme distinctions between the noetic 
or intelligible world and the aesthetic or sensible world built 
up by Plato and his successors were destroyed. The truth, 
which it now concerns us most to admit, is that empiricism 
is in its last agony, that we start with reality, with sensible 
reality indeed, but still reality, and that herein lies an 
essential difference between man and the animal. Thought 
is not a temporal afterthought; it works by means of sense 
and in dependence on sense, but it is instantaneous in the 
composite act of man which tells him that he is aware of 
some sensible real thing. I should like to go on to show that 
no sound theory of what is called the universal can be given, 
unless we grant that the particular can never be given first 
and in isolation, but I must hurry on to give two conse- 
quences of this truth. The first is that on this theory an 
escape from agnosticism is provided for science. Trusting 
itself alone and with no roots in reality, no sooner do its 
results fail to work out than it despairs and calls itself a 
maker of fictions. If, on the other hand, science recognises 
itself as a legitimate abstraction within an act of knowledge 
which of its essence grasps the real, then it should expect to 


Erogress alongside the real and to give a report which, if 
mited by abstraction and inadequate, is nevertheless drawn 
from that real and informatory about it. But it may be 
asked why are the methods of mathematical science em- 
ployed at all and with such desperate zeal by man if, as I 
say, the mind transcends sense and looks out on the fields of 
reality as they are in their own nature? The answer to this 
brings us to the heart of the matter. It is true that the mind, 
being a mind, is able to glimpse the intelligible, noumenal 
world; it is able to traverse it from end to end and recon- 
struct its ultimate and far-reaching principles, but the vision, 
though bounded by the real, is nevertheless imperfect. There 
is only one spot on which it rests with comfort, the terra 
firrna of the sensible. Kant was nearly right when he said 
that the mind needed the help of sense to escape from empty 
formulations. He wrecked his system when he went further 
and protested that we have no knowledge of the thing in 
itself. What he should have said is that we must have some 
knowledge, if we have knowledge at all and if empirical 
science is to stand, of the nature of reality, and that that 
must be eked out with the help of sense. If it be true that 
we are citizens of no mean realm of being, we have no intui- 
tion of it; we read its meaning through the veil of sense, 
through its appearances. Not that we first perceive appear- 
ances and then infer a reality; this may be necessary when 
we want to reach some particular cause or substance; but 
we always read through the phenomena something of the 
meaning and intelligible character of the universe. If also 
we are forced always to represent to ourselves what we know 
in terms of some image or material symbol, as we are proved 
to do by the very use of such words as apprehension, con- 
cept and understanding, we can transcend the limitation of 
the symbol and see that it signifies the intelligible though it 
represent the material. 

Now if this correction of current assumptions be accepted, 
then the function of mathematical science can be elucidated 
and a way opened for a theology worthy of the name. The 
idea of man as a by-product of a vast mechanical system or 


just a highly sensitive animal must end finally in a felo de se 
of man. But neither will the opposite extreme do, that all 
goes on in his mind or that he is the creator of values. The 
truth about him is both uplifting and humiliating; by reason 
of his mind he is, as Plato and Aristotle saw, godlike, and 
by reason of his limitations he has to look before and after, 
to use discursive reasoning, to work empirically for the most 
part. He can see dimly infinite distances, but he has to use 
his two feet to walk and explore them. The ancient pre- 
ferred to sit still and satisfy himself with what he could see 
in outline, the modern has found out a substitute in the 
mathematical methods, which resemble an aeroplane, with 
all the limitations that come from looking down on a flat 
surface. (To save misunderstanding, let it be remembered 
that in this simile the distances are seen by sense, whereas 
the vision of reality and its outlines is of the intellectual 
order and therefore indefectible.) Both procedures are right, 
both requisite. Physical science tells us about the material 
world in so far as it is calculable, and one of the charac- 
teristics, though not the only characteristic, of physical be- 
ing is that it is measurable and numerable; and again there 
are characteristics of the metaphysical world which are in- 
telligible, and even if they have to be represented to our- 
selves, because of our natural reliance on sense, in sensible or 
anthropomorphic terms, we can be sure that we are knowing 
something of the nature of reality and we can, by a method 
to be explained later, rectify the limitation imposed upon us 
by our way of thinking. 

The advantage of this theory of knowledge is that it 
brings within one sweep physical nature, the sensible world, 
man, and a possible highest order in which truth, goodness 
and beauty abide. There are no unbridgeable gulfs separat- 
ing science from philosophy and philosophy from theology. 
The fatal sharp distinction first imposed on the modern 
world by Descartes in philosophy between res extensa and 
res cogitans, and by Luther in theology between faith and 
reason, is destroyed. Science is not based merely on sensa- 
tion and it is not the only form of knowledge, and there is 


no need to place this over-reliance on human experience and 
spoil supra-sensible knowledge by calling it mystical or supra- 
rational, or, in a less confident mood, subjective and anthro- 
pomorphic. The harm caused by so doing has been con- 
siderable, as might be illustrated by the history of such 
terms as substance, self, nature and even idea; but one ex- 
ample may suffice, that of cause. The scientist, starting with 
a confused notion of sense-experience, kept the notion of 
cause both because at first he pictured atoms as infinitesimal 
billiard balls and because he persevered, without being fully 
aware of it, with some of the old metaphysical notions. The 
more, however, the mathematical methods came into force 
and the more he took over the standpoint of Hume, the less 
pertinent did the idea of cause appear. Now it is claimed in 
many quarters that there is no need of it at all. That may 
well be because physical science has chosen an aspect of the 
real which can be treated without it; at any rate that is for 
the physicists to decide. But the persisting presence of the 
notion is due to the fact that cause does belong to the real 
order from which science has abstracted its subject matter. 
Even the philosophers, however, have been frightened of say- 
ing this because in the train of Descartes they have broken 
the chain which united together in some sort the world of 
sense and the world of intellect, the realm of quantity, 
quality, life and spirit. Hence they took their own experience 
of causality as subjective, as peculiar and doubtful, and con- 
sidered that it would be anthropomorphic and illegitimate to 
transfer it to the physical world. And so arose the habit of 
speaking of logical connection as if it had nothing to do 
with connections in reality, and of laws of thought which 
ruled no kingdom of the world. Such a philosophy, thank 
heaven, is no better than a nightmare, and the truth is that 
our thought from the beginning takes its complexion from 
reality, and that just as it is impossible to think without 
using the category of ground and consequent, so it is impos- 
sible to think of reality without the principle of causality. 
That is not to say that cause is used in exactly the same 
sense of matter, of will and of God. There are various orders 


within the real and the differences between them are not 
merely nominal; matter is not spirit nor spirit matter, and 
yet they are not wholly alien; they both exist and are some- 
thing, and this unity is not just nonsense, a flatus vocis idly 
used. Even God falls within this dark majesty of being, and 
that is why our thought of Him touches reality, though from 
afar off. And so it is that we meet cause in every order of the 
real. The scientist confesses to this because his inquiry in- 
volves the questions, why and wherefore, and though by a 
self-denying ordinance he confines his further inquiry to 
phenomena and their succession, even there he stands on the 
brink of real causes and profits by the fact in the applied 
sciences. Human beings, again, know what self-determina- 
tion is and see the analogy which exists between the world 
outside, their own bodily activities and their will; and lastly 
God fulfils in His own way completely the meaning of cause, 
for, whereas in nature and in ourselves the why and the 
wherefore had to be sought beyond the event and beyond 
our own existence and life, God is his own explanation; He 
requires nothing to support Him or render Him intelligible; 
He is complete and dependent solely on Himself; He is 
therefore cause in the fullest sense of the word. 

It remains, now that the way has been opened to a science 
of theology, to show it at work. The modern way, as I have 
pointed out, is to begin with experience. In so far as that 
means that we can start with the fact that most, if not all, 
peoples have believed in the existence of a God or gods and 
held certain beliefs about them, it can be accepted. The task 
of theology is to scrutinise these beliefs and all relevant reli- 
gious data and ask what validity they have. This procedure 
is common to all scientific inquiry, but there is this pecu- 
liarity about the data of theology, that the object of the 
belief is not sensible or visible and that it is bound up with 
values, even ultimate values. I do not mean, of course, that 
the gods have not often been pictured and imagined as vis- 
ible. It is indeed a confirmation of my argument above 
about the nature of our thinking, that man nas habitually 
tended to represent to himself the divine being in physical 


shape, but it must be taken for granted for brevity's sake 
that God is by nature immaterial. Now, this being so, a 
free-thinker like Lord Russell is at liberty to suggest that 
religion is just a mode of escape from a frightening universe 
or animistic illusion or childish fancy. On his side the the- 
ologian must try to show that such a hypothesis does not fit 
the data, and if he believes in the possibility of philosophy 
he will be prepared to argue, from any positive datum his 
opponent may like to choose, that there must be a God, and 
will challenge the sceptic to find a flaw in his argument. 
This, I think, is the better method if it can be followed, as 
it leaves the field of hypothesis for strict argument. But, as 
already explained, it is not usually followed owing to the 
general distrust of the mind's power to extend beyond ex- 
perience. Instead, we have arguments of the following kind. 
As a phenomenon, religion cannot be dismissed as unim- 
portant. In the beginning it played a vital part in the life 
of the community; the early communities, so far from being 
confined in their thought to their immediate physical needs, 
are, if anything, too dominated by the sense of the preter- 
natural and by religious beliefs. Nor is that religion just a 
mass of superstition; it is rather the vague conception of an 
" ocean of supernatural energy " and has for its root that 
sense of dependence from which all the highest manifesta- 
tions of religion spring. " O You who possess the skies. I am 
living. I in you entrust my fate again alone upon the war 
path/' as the Pawnee warrior sings. If, then, as the evidence 
seems to show, religion is the strongest force in the develop- 
ment and preservation of a culture, it must be taken seri- 
ously. We are all the more bound to do this when we regard 
its highest manifestations in the world religions and par- 
ticularly in Christianity. An experience which can produce 
such high types of manhood as are to be found in the saints 
and bring before mankind such high values as the mystics 
speak of, must be given full measure in any worthy interpre- 
tation of life. And so it is that these experiences can be 
gathered together and given the status of a branch of know* 
ledge which, if distinct in aim and method from that of the 


sciences, deserves nevertheless to be included within a 
general philosophy of man and the universe. 

The correct method to be followed in theology, what may 
be called the philosophic method as opposed to the scientific, 
may be explained in the following way. The scientist, deal- 
ing with a branch of knowledge, one carefully selected field 
of operation, one, moreover, so delimited as to suit his 
method of observation and experiment, is not concerned 
with general principles and truths which are antecedent to 
his study. He assumes what is necessary and only what is 
necessary to help him forward, and he is at liberty to make 
any hypotheses he likes so long as he can verify them. The 
philosopher and the theologian, on the other hand, have the 
duty of clarifying the first principles, of searching out what 
must be, if there is to be anything at all; and so the philos- 
opher asks whether there can be any such thing as know- 
ledge at all, wherein its nature exists, what is the relation of 
its object to it, what different kinds of objects there can be, 
what sort of being, again, a knowing subject must be and 
how he is related to his desires, whatever they may be, and 
so on. If the scientist takes for granted observation, the 
philosopher examines its meaning and possibility; if the 
former again finds the notion of evolution fruitful, the 
philosopher analyses it and points out that it can have no 
meaning without an unchanging background, that without 
a permanent unity of some sort changes would be unrelated 
and bewilder us like a perpetual Jack-in-the-Box. What, 
then, the theologian has first to do is to show that change, 
contingency, the imperfect, the relative, imply something 
absolute, and he concentrates his attention on what this 
absolute must be. 

This procedure is clearly different from that of science, 
and roughly it can be described as deductive. It consists in 
examining what is supposedly ultimate, criticising this by 
means of the first principles of reason, which are in their 
turn subjected to an analysis, and so establishing what must 
be and what follows from the admission of these ultimates. 
The subject matter of philosophy is therefore one which of 


its nature remains constant, and it may be said to cover that 
body of experience which is at the same time the most pro- 
found and the most common, that great human heritage 
which draws together into one family people from all times 
and from all the ends of the earth. It is to be found recorded 
in the Greek anthology, in the tombs of Mycenae and the 
papyri of Egypt, as in Shakespeare and the modern novel 
the love of a mother for her child and a child for its toys, the 
melancholy over the passing of what is fair, the respect for 
justice which drove Antigone to her fate, the longing felt by a 
Socrates for perfection, the warp and woof of life, the mystery 
of the self and its destiny, and God. Reflection on this com- 
monwealth provides the philosopher with his material, and it 
was as possible for a wise man of the Egyptian dynasties, or 
Periclean Athens, to arrive at the truth about most of these 
matters as it is for a thinker of the twentieth century. 

It would seem to follow from this that theology does not 
advance in the same way as science. Certainly it differs from 
science, and the complaint of Kant against it that it is 
stationary is really its glory. There must be at least one form 
of knowledge which escapes relativity if we are to have any 
standards at all and avoid complete scepticism. It is never- 
theless more accurate to say that it does advance, though 
in a way different from that of science. Theologians some- 
times use the word development to describe this, and two 
considerations will show what is meant. A child has some 
distinctions in its mind between the pleasant and the hurt- 
ful, between good and bad; it is taught proverbs and maxims 
and it clothes invisible beings in fanciful and sensible garb. 
In time it comes to realise what has been so far notional, to 
grasp vividly, for instance, such a saying as * that it is sweet 
and fair to die for one's country/ and to discard the pictorial 
when meditating on spiritual realities. There is here a 
growth; meanings are realised and new relations understood. 
Now what happens to the child happens, too, in the advance 
of culture; the habit of imagination gives way to philosophy; 
the interest in external nature, in other men and women, in 
new worlds to conquer, as seen in the first vigour of Athens 


or Elizabethan England, in the beginnings of novel writing, 
is succeeded by a new taste for which the self is the subject 
and the psychological novel the ideal. This seeing of 
what is permanent in new situations causes an advance in 
knowledge different from that in science. The second con- 
sideration bears less on theology than on other branches of 
philosophy. It is this, that though philosophy, as I have ex- 
plained, has its own domain, the boundaries between it 
and science are not always clear cut. This is well seen in 
psychology; the problems of perception, of consciousness, of 
freewill, of the self, of the relation of the mind and body 
can be rightly claimed, I think, to be philosophic, and there- 
fore as open to a right explanation from a Plato as from a 
Bergson, but, in fact, a modern writer ought to be better off 
because he knows far more about physiology and biology 
and so can avoid the temptations which beset the earlier 
philosophers to generalise beyond their premises and take 
over assumptions which subsequent science would show to 
be unjustifiable. 

The theologian, taking the data of human experience, 
seeks to show a rational foundation for it and formulate 
what is confused in clear conceptions; and he also holds that 
the proper way to do this is to launch out on to the sea of 
reality with confidence in the power of the intellect to appre- 
hend something of the ultimate nature of that real. The 
majority of philosophers have followed this route, Plato, 
Aristotle, Aquinas, Descartes, Leibniz and others, though 
since the time of Kant it has been abandoned by many. 
Kant's position precluded him from using arguments resting 
on the real as it is in itself and he criticised the old proofs 
as unsound because they contained as an implicit premiss 
the old ontological argument. His point comes to this : the 
cosmological argument relies on two premisses; 'being 
which is contingent or conditioned involves the existence 
of being which is necessary or unconditioned' and 'neces- 
sary being is supreme perfection/ Now in the second 
premiss it is only because the notion of perfect being is 
thought to involve necessarily its own existence that the con- 


elusion follows and this assumption is illegitimate. This 
criticism would be valid if Kant's theory of the limitation of 
our knowledge were correct, but other philosophers and 
scientists who do not accept his account of knowledge have 
no right to quote his conclusions, unless they arrive at them 
by an independent argument. It is their assurance, I fear, 
which contains what Kant called " a perfect nest of dia- 
lectical assumptions," such as, for instance, that the category 
of causality belongs only to the world of phenomena and 
may even be discarded there, that an infinite series is pos- 
sible and that therefore the argument to a first cause has no 
validity, that one cannot get out of experience more than is 
contained in it. None of these objections touches the clas- 
sical arguments for the existence of God, for they ignore 
the claim of the orthodox theologians that metaphysics is 
possible. This claim is not just an assumption; it is the con- 
dition of knowing and implicit in all assertions of know- 
ledge. If I can never say that a truth is so sure that no 
further knowledge of reality can contradict it, then I can 
be driven finally into complete scepticism, and that itself 
would involve one inexpugnable truth. Now if there is a 
single truth which it is impossible to contradict, it follows 
that I know something about reality which holds true in 
every domain of it, that I have broken down the barrier 
which appeared to restrict me to one category of being. 
There is no truth, therefore, in saying that out of finite ex- 
perience I can get only finite reality, that the notion of cause 
is empirical and, as such, inapplicable to metaphysical con- 
ceptions. Of all that is and can be I know something and 
something sufficiently common to allow me to pass from 
one part of reality to another, from matter to spirit, from 
the sensible to the intelligible, from the contingent to the 
absolute. These various orders are not entirely disparate, 
as many, following Descartes, have maintained or implied; 
I can make statements which hold good for them both and 
for any possible order, even the divine, if it exist. It is a mis- 
take, therefore, to say that we know only the material, the 
sensible, the phenomenal or only the spiritual, the concep- 


tual, or that the two are totally alien the one from the other. 
It is also an unjustified assumption to say that what we call 
the real is limited to what we experience and at most con- 
ditioned and finite. In our very first judgment we transcend 
experience, for we say that something is such and such, and 
it may be that both from the point of view of the judgment 
and from the nature of the object asserted to be, we may be 
forced to affirm also some existent, absolute subject or being. 
And this is precisely wHat the theologian does affirm when 
he says that existent, contingent being implies an absolute 
being or source and that every act of judgment, being in its 
own way absolute and yet progressive, can be explained only 
as a function of some absolute or in virtue of it. 

All who admit the possibility of metaphysics and the 
alternative is a self-destructive scepticism will be bound to 
agree with what has just been said. It belongs to the prole- 
gomena of a sound theology. What we have now to deter- 
mine is the nature of this absolute or whole, for the pre- 
liminary remarks just made are at a first glance compatible 
with the views of a Spinoza, a Hegel or an Aquinas, with 
monism or monotheism. The arguments used to prove it go 
a certain distance to show what its nature must be, the argu- 
ments, namely, from effects and from contingency, from 
dependent essence and dependent existence, and they can be 
supplemented by evidence from design, from conscience and 
the unsatisfied urge of our nature to an effortless beholding 
of complete truth and the possession of what is infinitely 
desirable. The arguments, I say, can carry us a certain dis- 
tance. If a distinction in the real order is required between 
what is absolute and what is contingent, between the de- 
pendent and the self-sufficient, then it is enough to show 
that what is perishable and finite is not mere appearance, 
for a solution on the lines of pantheism or monism to be 
ruled out. The perfect and unchanging cannot be composed 
of what is limited and changeable, and I might add that the 
expression, Reality as a Whole, is even more misleading 
than the word Nature. There must be some kind of mean- 
ing in the expression, and some kind of unity which allows 


us to call anything whatsoever real, but this unity must be 
compatible with real differences and substantial differences. 
The relation of a human being to nature is different from 
that of a tail to the dog to which it belongs; we cannot class 
together under one identical name such variously assorted 
objects as thoughts, trees, penguins, cocktails, unicorns and 
persons. If we take persons, for example, we imply a certain 
kind of nature, privacy within that nature and a degree of 
independence and unshared responsibility. What kind of 
relation can they have to that which has been proved to 
exist, namely, a real object or subject which is completely 
and supremely real? It is manifestly impossible to work out 
in a few lines the answer to this difficult question, and so I 
must be content with just stating dogmatically the conclu- 
sion that since the nature of human persons, though perfect 
in its kind, is essentially limited and their existence finite, 
they must be dependent in these two regards on a being 
which in its turn, being complete and absolute, must be 
transcendent, sovereign and personal. 

To call this supreme reality personal will seem to many a 
step quite unjustified by the argument just given. Even 
those who are ready to admit a metaphysical discussion of 
the kind I have sketched make a sharp distinction between 
the god of philosophy and the God men worship in religion. 
Philosophy, they say, may serve to prove the existence of 
some vague, abstract, absolute or necessary being, but this is 
little more than a confession that something must exist, 
which for the sake of a word may be called (Irvine, though 
its nature be unknown. Religious experience cannot be con- 
tent with such a dark mystery and overcomes the difficulty 
at a cost; it takes the best that we can think in the way of 
human ideals and so clothes God with personal attributes. 
He becomes majestic, wise, just, loving and lovable. Is 
this justifiable? Many would distinguish in their reply be- 
tween the certainty of philosophical truth and the certainty 
needed for religion. The former is absent from this pro- 
cedure, but religious experience does justify us in regarding 
God as personal and loving. If we look at history we find 


that mankind has chosen one of two ways in its theology; 
either, like the Hindus, to renounce all description of God 
and in that renunciation find peace, or make up a ' myth ' 
as worthy of him as possible. The West has followed the 
latter way, creating God after its own image, and experience 
has shown that it must contain some truth, no matter how 
anthropomorphic that truth be. 

Now in this explanation the necessity of anthropomorphism 
is taken for granted. If, as I believe is possible, human think- 
ing can escape this weakness, theology will rest on far surer 
foundations. No doubt the habit of humanising God has 
been very prevalent in religion, but that does not prove that 
it is necessary; and if what I have said of knowledge in a 
former paragraph be true, the means to overcome the habit 
are at our disposal. Human knowledge has two character- 
istics, that it is true and that it is limited. As true, it encom- 
passes the whole realm of the real; as imperfect, it is suited 
to focus on only one province of it, the province of the 
sensible which can be measured. To put this in another 
way. If we suppose that an animal, such as a fox, is without 
reason, then the acquaintance which it has with external 
objects will be limited by its organism and animal faculties, 
and it will interpret all by its own experience and have no 
interest in things as they are in themselves. That is why an 
animal has no absolute standards in conduct, is indifferent 
to beauty and humour and knows nothing of truth. As 
Xenophanes of Colophon said, " a horse would call the gods 
a horse, an ox, a god ox-shaped." On the other hand, the 
differentiating mark of man is that he can know objects, not 
in terms of himself, but as they are in themselves, and 
though he finds this very difficult, by dint of reasoning and 
induction and the very power of the mind itself to criticise 
itself, he can succeed to some extent. 

To see how this can be done let me recall one or two 
observations already made. The significance of our concep- 
tions goes beyond what they can be said to represent. For 
instance, some of the recent conceptions of the universe are 
quite unimaginable, and we have always to be careful of con- 


fusing what we may be bound to think about space or time 
with our fancy or imagination of them. Again, while we 
may be convinced that plants and animals have life, and 
that animals have a sensitiveness and awareness akin to our 
own, the differences are so striking as to forbid us to identify 
their experience with our own. A dog, if it could give the 
subject thought, would be wise in surmising that some of its 
master's behaviour showed anger, and wiser still if it guessed 
that the anger differed in many respects from its own. Now 
this principle of comparison and judgment can be applied 
to beings who are as much above us as animals are below us, 
and it is applicable even to God. If we find in ourselves or 
other things or persons any characteristic which in its pure 
condition is without flaw, we can attribute it to God, keep- 
ing in mind at the same time the proportion which must be 
observed between it as embodied in a finite object and in the 
divine being. By this means we are enabled to escape the 
Scylla and Charybdis of Hindu negation and anthropo- 
morphism. Our thoughts, so to speak, circle round God and 
are not lost in the empty air, but before they can be said 
to be true of Him they have to be divested of the human 
livery with which we clothed them. If we ask can God be 
spatial or in time, developing or stationary, harsh and re- 
vengeful, forgetful or reflective, we can answer straightway 
in the negative, for all these characteristics imply by their 
very nature imperfection of some sort. If, on the other hand, 
we ask can God be just and loving, wise and personal, we 
must reflect on these qualities to see if they contain within 
their meaning any flaw. Wisdom, for instance, may well be 
perfect, for it means that to the possessor of it there is noth- 
ing hidden, that he can enjoy in the most intimate way con- 
ceivable all that is and all that can be desirable. That such 
a form of knowledge is possible we have no reason to doubt, 
though it is far different from our own. We have no 
acquaintance with it, and consequently when we attribute 
it to God we have to free the word wisdom from all the 
limitations we impose upon it. Like the dog in its medita- 
tion on anger, we attribute rightly the virtue of wisdom to 


God, and so make a correct statement about His nature, 
while at the same time we refrain carefully from calling our 
wisdom God's. 

This is the method whereby we elaborate a theology, and 
analyse with what truth and in what sense we can speak 
of God as cause and end, as transcendent and immanent, 
and by means of it we can bridge the gulf which separates 
the necessary being of philosophy from the God of religious 
experience. Thus both parties are mutually benefited, for 
theology is relieved of its abstractions and religious experi- 
ence is rinsed by cold thinking. It must be confessed, how- 
ever, that even so our knowledge of God and His ways 
remains very dark. The highest religious experiences are the 
reward of the few and they cannot always be communicated, 
and our thought about God, while, as I have explained, it 
can be true and informative, remains nevertheless oblique 
and fringed with mystery. Nothing else, of course, could be 
expected; indeed, if a writer were to make God easy of access 
and neighbourly, such familiarity would be almost a certain 
sign that he had lost sight of the true nature of divinity. 
This is the element of truth in the old saying that no one 
could see God and live. 

And with this I may end, as I have contented myself with 
trying to describe what human thought and human experi- 
ence left to itself can do to make a science of God. There 
is another theology which claims to rest not on what man 
can think of God, but on what God has deigned to say of 
Himself to man, and this is the specifically Christian the- 
ology. Though it claims to be in accord with reason, its first 
principle and ground are not reason but divine authority 
and revelation, and therefore it would need a new chapter 
to describe its method and subject-matter. Nevertheless, it 
can be invoked to throw light on the certain and tentative 
results of the theology of which I have been treating. This 
latter is bound by its very nature to leave much unsaid, to 
record far-off facts, leaving their relation in a luminous mist. 
It is the noblest of all studies and at the same time the most 
humiliating; it keeps itself straight by reliance on the most 


fundamental principles of human thought and by discover- 
ing a means to apply what is best in human experience to 
God without error, due regard having been paid to the rela- 
tivity in our ideals. But apart from the difficulty of keeping 
one's head on the soaring pinnacles of such thought, it is 
humiliating to realise the imperfection of it. There may 
seem to be proof, as Sir A. Fleming has said, " that the 
physical Universe is not in itself eternally enduring," that 
it is "not, therefore, self-produced or self-maintaining, but 
the result of a Creative power, and requires a continually 
operative Directive Agency. There are unquestionably in 
the physical Universe things that stimulate our appreciation 
of order, beauty, adaptation, numerical relations, and pur- 
pose in our minds we who are thinking, feeling persons 
and hence the qualities which excite these psychic reactions 
must have been bestowed on the Universe by a Sentient 
Intelligence at least as personal as ourselves/' We may agree 
with Dr. Whitehead that there must be a God as a source of 
limitation and determination in nature, " the one systematic 
complete fact, which is the antecedent ground conditioning 
every creative act/' We may be sure that the world, whether 
it be supposed to be eternal or temporal, is dependent on 
something else for its existence and continuity, that its 
meaning has not been imposed on it by us, that the labours 
of science go only to make these truths more manifest. 
Nevertheless, when all has been said and thought, we see 
only the shadow of God's nature and know only the rumours 
of His presence. The last word of unaided human thought 
on the relation of God to the Universe, the problem of pre- 
destination and freewill, the meaning of evil and the final 
destiny of man, is such that it raises as many questions as it 
answers, and there is no unlocking of the many seals of the 
divine volume unless God should deign of his own accord 
to make himself known by Revelation. 



Professor of Chemistry in the University of Durham 

THE older text-books of chemistry often began with 
a definition of the science " Chemistry is the study 
of the composition of matter," or some such sen- 
tence. But a science defined is a science dead, a moored 
hulk; and chemistry is emphatically not that. For a writer 
to attempt to define it now would argue himself either in- 
experienced or fossilized; and it seems that the only way in 
which a broad view of the science may be gained is to glance 
at the main themes that actually invite practical and per- 
sonal study by men who are hailed as chemists. It is easier 
to say who is a chemist than to say what chemistry is; for it 
is a subject " whose margin fades forever and forever as we 
move/' and it has many margins. 

Look, for example at the " Annual Reports of the Progress 
of Chemistry " which the Chemical Society has issued for 
the last quarter-century; and notice the titles of the various 
surveys in any one year : General and Physical Chemistry; 
Inorganic Chemistry; Organic Chemistry Aliphatic divi- 
sion, Homocyclic division, Heterocyclic division; Analytical 
Chemistry; Biochemistry; Crystallography; Colloid Chemis- 
try; and a special report on the Structure of Simple Mole- 
cules. Geochemistry; Radioactivity and Sub-atomic pheno- 
mena; these are two other main headings recur 
almost every year. Here is variety enough; ar JL even so, 
almost every separate reporter pleads that he c? a deal only 
with a few of the advances that the year has brought forth 
in his own branch of the subject. It may also be noticed 
that the materials have been drawn from some 200 weekly 
or monthly research-periodicals, of which, though most are 



specifically entitled " chemical," many lap over borderlands 
into sister-sciences. 

It would seem at first sight that in chemistry the day of 
the 'Forty-niner' is over; that we have passed the simple 
alluvial stage of " placer-mining " for our chemical gold. It 
is perfectly true that most chemists hew and drill at the 
working faces of galleries which their predecessors had 
driven and opened up. Nevertheless, we still have with us 
and shall have the pioneer prospectors who seek out fresh 
deposits and, when they find them, inaugurate a "rush"; 
which itself will later steady down into more hum-drum 
deep-working in much hard rock, or even into the raking 
over of old waste-heaps for the sake of good gold still unwon. 

Suppose that we first examine generally the technique of 
chemical investigators, thereafter asking what it is for. 
Broadly speaking, chemical technique is of two kinds : quali- 
tative and quantitative. The qualitative is what answers, 
more or less, to the nai've lay idea that "experimenting is 
puttings things into test-tubes and seeing what they do." It 
is the comparison of substance with substance : the recogni- 
tion of materials, and of the fresh materials which they yield 
when intelligently intermixed, or when submitted to such 
agencies as heat, electricity, light. Quantitative chemistry, 
on the other hand, applies measurement to all such sub- 
stances and to all such reactions. Its practitioners wish to 
know "How much?" before they can answer "What?" and 

The coexistence of these two forms of technique, though 
it is not peculiar to chemistry, is especially characteristic of 
it. It should not be thought that, because quantitative study 
follows historically after qualitative, it is intrinsically the 
superior method. Each is a salutary and necessary check 
upon the other, each buttresses the other and reveals new 
fields of exploration for both; and neither can go very far in 
safety without the other's support. Measurements, in the 


last resort, stand or fall by qualitative tests of identity. We 
might measure two triangles and find them equal, but it is 
their superposition without visible overlap which convinces 
us that the measurements were right; so, likewise, chemical 
judgments ultimately turn upon samenesses or unlikenesses, 
put to qualitative proving ad libitum. Without, however, 
straying into the philosophy of measurements, we should 
understand plainly that the qualitative, non-numerical aspect 
of chemistry remains an integral part of the science. Herein 
it differs, I think, from physics, which demands measur- 
ability in all that it handles. Physics did not and could not 
begin to take cognizance of chemical discoveries until these 
had been developed quantitatively by " physical chemists," 
who had themselves conjoined the functions of the physical 
measurer with those of the chemical " experimenter." And, 
conversely, the same intermediaries are constantly intro- 
ducing their qualitative brethren to the discoveries of 

We may select, from among the larger chemical advances 
of recent times, one which exercises especial dominance 
today. This is to put it succinctly the electrical character 
of the chemical atom : not solely as shown in a scrutiny of 
that atom's inward parts, but as evinced in the external 
properties of the atom and of groups of atoms. There are, 
in chemistry, very few old facts, and hardly any of the 
newer discoveries, of which the current explanations do not 
invoke electrical agencies. In this essay we need not engage 
in much historical retrospection; but it is well to recog- 
nize that the assumption of an electrical nature in atoms to 
explain their chemistry was being made long before any- 
thing definite was known about the internal architecture of 
an atom. We forgot, or had laid aside, the century-old idea 
of Berzelius that an atom or a molecule could be a " dipole " 
that is, could have an electropositive head and an elec- 
tronegative tail; but now, in another form, this is the essence 
of much of the foremost chemistry of today. 


Looking back, we can see that inter-atomic action and 
molecular structure were studied from two points of view, at 
first very different and even opposed, but now brought very 
near together. Organic chemistry since 1874 utilized the 
idiosyncrasies of the carbon atom to study valency the 
direction and the tenacity of the force linking atom with 
atom. If, in the course of this, organic chemists incidentally 
engendered new industries such as the manufacture of syn- 
thetic dyes; if they brought to light the nature of many 
natural drugs, and enabled these to be made for use and 
many new medicinal compounds to be invented; all this, 
part of the great economic contribution of chemistry to the 
world, while it is an earnest of the power of accurate re- 
search, is really a by-product of it. Scientifically, the main 
issue of the multitudinous studies which arose from the work 
of Pasteur, and later van't Hoff and Le Bel, and which in- 
cluded the long labours of such men as Wislicenus, Baeyer, 
W. H. Perkin, Jun., and their innumerable disciples, may 
be surveyed (very inadequately) when taken in conjunction 
with the major issue of the other branch of chemistry. 
Physical chemistry, with Faraday to match Pasteur, really 
appeared in 1886, with van't Hoff again as founder of it, 
coupled with Arrhenius in Sweden, and with Ostwald in 
Germany as their prophet. Their ionic theory for many 
years almost a generation interested organic chemists even 
less than organic chemistry interested physical chemists: and 
indeed, there are even now persons in one or other of these 
two folds who inherit the prejudices of those times. 

In broad outline, the story is this. Pure chemical com- 
pounds can be roughly divided, by their behaviour, into 
two sorts. Those of one sort are marked by great quickness 
in their mutual reactions; the component atoms of two 
different molecules can change one partnership for another 
with no detectable delay, as soon as they are brought 
together in some suitable medium (usually water). In this 
class of compounds are acids, alkalis, salts; that is, more 
particularly, inorganic compounds. On the other hand, the 
substances of the second sort act upon one another much 


more leisurely. Water, which so often serves as a dissolvent 
medium for the members of the former class, is less com- 
monly of avail here, except in the natural laboratories of 
living organisms; but in any case the chemical interactions 
concerned are sluggish. The greater number of compounds 
in this class are organic compounds compounds of carbon, 
with other elements such as hydrogen, oxygen, nitrogen, sul- 
phur, chlorine; and they are usually complex, their mole- 
cules being composed of strings or circlets of carbon atoms, 
with the other atoms attached. But the distinction be- 
tween these two great classes is not simply dependent upon 
the presence or absence of particular kinds of elementary 
atoms in the molecules. For almost any of the ninety ele- 
ments can form part of a compound of either class. Clearly, 
then, the distinction lies rather in the ways in which the 
atoms composing a molecule, whatever their kind, are tied 
together; there must be loose linkages in the one class of 
molecule, tight linkages in the other. 

The ionic theory started from experiments which show 
that the instantly-acting compounds are made of molecules 
which spontaneously split into smaller parts (" radicles "); 
and further, that these separate radicles, which are either 
atoms or small groups of atoms, are electrically charged, 
some positively and some negatively. These charged radicles 
are the "ions." On the other hand, the characteristically 
sluggish molecules of the other sort, with which organic 
chemistry largely deals, do not split up into ions. Their 
atoms preserve their pattern through a series of chemical 
vicissitudes, and are evidently more tightly bound together. 

An early difficulty was that for a salt or acid or alkali to 
dissociate into electrified ions, there seemed to be required 
the addition of water, or else some other suitable liquid. 
Not all liquids would do this to the compound; but on the 
other hand, merely melting the pure substance by itself 
would suffice. In recent years this difficulty has been met by 
the discovery (partly due to work with X-rays) that a com- 
pound of this class is always ionized, no matter whether it 
is a pure crystal or has been dissolved in a liquid or has been 


melted. The solid crystal is held together by the reciprocal 
attractions of the oppositely charged ions; and what me act 
of dissolution in water does is to enable the ions, already 
there, to float apart, helped by each ion's becoming attached 
to water molecules that act, as it were, as buffers between 

So we arrive at the view that the force linking the com- 
ponent parts of a molecule of the highly reactive type is 
electrostatic : the same that makes a scrap of paper cling to 
a rubbed fountain pen, or hair crackle with a comb. It is a 
force which is easy to mitigate, so that the ions are loosened 
and can play " general post." 

Yet consider another set of facts. Loose as ionic (or, to 
give them the better name, " polar ") compounds are, never- 
theless their crystals are far harder to melt down by heat 
than those of the other, the non-polar compounds. We must 
clearly distinguish between two tenacities; the electrical 
tenacity of the huge aggregate of ions, -f and , which is a 
crystal of a polar compound; and the chemical tenacity of 
the small aggregate of neutral atoms which is the molecule 
of a non-polar compound. An electrically neutral molecule, 
the molecule of a non-polar compound, exercises little force 
on another of like kind, and so a packed mass of them the 
non-polar crystal is easily melted by heat. 

It may now be seen that physical chemists were really 
studying inter-iora'c linkage the union and disunion of 
electrified atoms; while organic chemists were studying inter- 
atomic linkage the union and disunion of electrically- 
neutral atoms. In this latter study, organic chemists made 
great strides, and learnt to map out the structure of the most 
complex non-polar molecules with uncanny certainty. They 
could assign directions in space to the chemical force linking 
one atom to another, and could show how, by merely chang- 
ing the sequence of the atoms in a given chain or ring, the 
strengths of the various linkages are affected. They learnt 
what conjunctions of atoms and linkages will produce 
properties such as colour in a compound; and far too much 
else to hint at here. But they had not reached the point of 


assigning to all these inter-atomic linkages any underlying 
cause, even to the limited extent that we have just seen a 
partial cause for the inter-ionic links of a polar-compound. 

The origin of both kinds of linkage began to be clear after 
the discovery of electrons. Thirty-five years ago, J. J. 
Thomson detected and measured the electron in gases under 
electric discharge; and he showed that the electrical charge 
which it carries is of the quality arbitrarily called "nega- 
tive," and in quantity is the same as is carried by a chemical 
ion. He also showed that electrons can be liberated from all 
sorts of substances that is to say, they are constituents of 
every kind of atom. 

Here was the first evidence of any structural complexity in 
the atom; and naturally, it was to this new sub-atomic unit 
that chemists afterwards turned their attention, when they 
began to seek an origin for their " valency-bonds " between 
atoms or between ions. From the first discovery of the intra- 
atomic electron it was clear, however, that it could not be 
the sole ingredient of an atom; for the electron is negatively 
charged, whereas the atom as a whole is not electrified, and 
it must therefore also contain some positively charged in- 
gredient to make the complete organism neutral. Also the 
atom has weight, the electron hardly any. Radioactivity, in 
the hands of Rutherford, and of Soddy and Fajans, even- 
tually gave the required information, and established in 1911 
the " Rutherford model " of the atom : planetary, negative, 
weightless electrons encircling a central, positive, massive 
nucleus. Moseley's work with the Braggs X-ray spectro- 
meter completed beautifully the correlation of this model 
with the chemist's atoms; this work finally awakened 
physicists to the virtues of the old-established chemical 
ordering of the elements, and it has also been of the greatest 
value to chemistry by "calling the roll" of the existing 
elements, and as a weapon for discovering some others for 
which gaps had had to be left in the Periodic Classification. 

It was shortly after this that G. N. Lewis put forth his 
fertile hypothesis of electronic linkage between atoms, which 
has re-united organic and physical chemistry, and has un- 


doubtedly given the whole science fresh impetus. This is not 
the place for detail; the barest outline alone need be recalled. 
On the one hand, Lewis, in agreement with Kossel and 
others, ascribed the formation of a polar link between two 
atoms to the transfer of constituent electrons from one atom 
to the other; one atom thus receives negative electricity, be- 
coming a negative ion, while the other, losing negative elec- 
tricity, is left as a positive ion. The two new entities then 
cling together by electrical attraction. Such a transfer could 
only occur, naturally, if each of the resulting ions has a more 
stable electronic structure than the original atoms had; and 
it was shown that in fact the number of electrons so trans- 
ferred usually adjusts matters so as to leave each ion with 
what is independently known to be a naturally stable 
number of electrons. The criterion of stability was laid 
down by Ramsay's " Inert gases " the six elements from 
Helium to Radium Emanation in which a proof of a maxi- 
mum of architectural stability is the fact that they refuse to 
enter into chemical unions, and are also of all elements the 
most difficult to ionize by other means than chemical. On 
the other hand, Lewis conceived non-polar linkage as a kind 
of pooling of the electrons belonging to two neutral atoms, 
neither of which could afford to transfer electrons wholly to 
the other without deprivation beyond the number required 
for its individual stability. More shortly, the two atoms 
share electrons, in pairs. 

Between the two modes of atomic linkage by electronic 
transfer or by electron-sharing it is difficult to draw an 
absolute distinction, and indeed the meaning of " sharing " 
electrons was for some time left obscure. But the last few 
years have seen a further great advance, chiefly contri- 
buted by physicists and lately by mathematicians. Niels 
Bohr took up Rutherford's atom, and made a synthesis of 
two distinct fields of science. That vast generalization of 
experimental chemistry, the Periodic Classification of the ele- 
ments, was one of these fields; the accumulated masses of 
numerical data in spectroscopy formed the other; and Max 
Planck's hypothesis of energy-quanta, applied to Ruther- 


ford's atomic model, gave Bohr the plastic idea with which 
he sought to bind together physics and chemistry. 

Bohr's quantum theory is, like every theory that is of any 
use, ad hoc] but " hoc " here is such a millionfold aggregate 
of knowledge that the ultimate validity, if not the pro- 
visional expression, of the hypothesis is taken as established. 
Experimentally it has forced chemists to recognize that their 
molecules and their individual atoms are internally adjust- 
able, by the access or release of energy; they are studying 
the steps by which an atom can be raised from lifelessness 
to increasing degrees of excitation until it can attack other 
atoms, or even cross a threshold so as to become an ion. 
The detailed aims, and still more the methods, of such 
studies are far beyond the scope of this article. One may, 
however, refer to the great body of studies of catalytic 
action, organic and inorganic (which action, by the way, is 
the foundation of much of modern chemical industry); 
photochemical and thermochemical work; work on the mag- 
netic properties of pure substances; the beautiful researches 
of the laboratories of physical chemistry at Hamburg, on 
molecular rays; and the more purely physical and astro- 
physical developments of spectroscopy initiated by Fowler. 

It may be allowable to offer an idea of the atomic mechan- 
ism propounded by Bohr, by way of a rough analogy. In its 
relation to the outside world, an atom may be compared 
with a motor car with its engine, clutch, and gear-box. The 
engine may be running (the electron may be rotating in an 
orbit), but the car does no work upon the road (no energy 
passes between the atom and outside it) unless a gear is en- 
gaged and the clutch is in. Further, at a given engine-speed 
the car can be made to do more work on the road surface if 
a lower gear be engaged; less, if a higher. 

There is some effect akin to this in the atom; an electron 
can work now with one " gear " engaged, now with another; 
and there is nothing but "neutral" between. Bohr dis- 
covered the " gear-box " and defined the gear-ratios, in the 
machine which is the atom. (Whether the gear-changing 
is worked by a driver or by automatic " pre-selection " 


is dealt with by Professor Planck in another article in 
this volume, and I shall not follow this perilous analogy 

The most recent work along these lines has been highly 
mathematical, based upon the quantum wave-mechanics 
which was devised to account for discrepancies between 
Bohr's quantum theory and detailed refinements of experi- 
mental fact. In the hands of such men as Heitler and 
London, Pauling, Lennard-Jones, this is beginning to at- 
tempt the problem of what underlies the sharing or pooling 
of electrons which is the valency-linkage in most of the 
molecules of chemistry. But this work is in its infancy, how- 
ever fast it is developing; and it has not yet succeeded in 
being as good a weapon of induction as the relatively simple 
hypotheses which are guiding the majority of chemists, both 
physical and organic. 

It would be misleading to the reader if no mention were 
made of the recent extraordinary progress in at least one 
branch of applied chemistry namely, the increase of bio- 
chemical knowledge. The hunting-down of pure substances 
vital to the living organism is a task which requires the 
utmost skill of the organic chemist, and the use of reagents 
and practical devices of which he alone among chemists is 
master. The isolation of some of the vitamins from treated 
foodstuffs is the most recent example of the same powers 
that first isolated adrenalin and other pure hormones from 
the secretions of a bodily organ. But, as with adrenalin, the 
biochemist's attack on such problems does not end with the 
extraction of a pure (and often unstable) compound from 
highly complex tissues; having got his material and proved 
its biological properties with the help of physiologists, he at 
once embarks upon two further tasks. The first is to dis- 
cover the atomic constitution of the molecule of the sub- 
stance not merely, of course, its composition, for that 
analysis is very simple but the whole pattern and exact 
architecture of its atoms. This task may sometimes prove 


very long and difficult, needing many chemists, working in 
different countries, to clear up piecemeal corner after corner 
of the molecule's constitution, by successive degradations of 
its structure, just as is the case with some of the natural 
alkaloids. If this problem can be settled, the next step is to 
build up the substance from simpler compounds which any 
laboratory contains. Such a synthesis, if successful, may per- 
haps settle some still unexplained part of the first problem 
the constitution; in any case, it would open the way to a 
biochemical goal of the greatest human value namely, the 
artificial manufacture of a vitamin or hormone which 
could be administered so as to remedy bodily and nervous 
deficiencies of the population. This side of biochemistry (for 
it is only one part of that branch of applied chemistry) is 
still at an early stage, and much is to be hoped from it. 

Let us try to sum up the purposes of chemists' work. The 
objective of a given research or a series of researches (such 
as may occupy an individual and his collaborators for many 
years) may be one of three kinds. One, which is peculiarly 
the motive of those whom we recognize as the leaders of 
chemical science, is the simple desire to obtain a mental 
picture of observable processes, in terms of ultimate units. 
In saying this, one must not necessarily be thought to ex- 
clude the behaviour of " wholes " or aggregates; if an aggre- 
gate comports itself as a unit in respect of the process under 
survey, the student of the process will not need at once to 
analyse the aggregate into detailed parts. But such an 
analysis will sooner or later have to be made, if only to learn 
how far the behaviour of the aggregate is merely a summa- 
tion of the behaviour of its constituents. Holism, taken un- 
critically, would be a lazy acceptance without understanding. 
So the progress of a science like chemistry must take the 
analytical road; and that road has successfully led us to the 
expression of large-scale, visible processes of nature in terms 
of ever-smaller units; each class of unit crystal, colloid par- 
ticle, molecule, atom, ion, and perhaps some day proton and 



electron too being shown to owe its properties to the sum- 
mation of those of something still more subtle, or simpler. 
The reintegration, the summation, is usually an even more 
difficult work to carry out than the prior analysis; and be- 
cause of this, an onlooker has to be no less patient than the 
investigators, and to refrain from expecting prematurely 
wide integrations in processes which are still under dissec- 
tion. At intervals through it all, it is healthy to remember 
Francis Bacon's words : 

"For that school is so busied with the particles that it 
hardly attends to the structure; while the others are so lost 
in admiration of the structure that they do not penetrate to 
the simplicity of nature. These kinds of contemplation 
should therefore be alternated and taken by turns, so that 
the understanding may be rendered at once penetrating and 

It will readily be believed that for the chief objective of 
chemistry the attaining of pictures in the mind's eye 
there are pressed into the service numbers of investigators to 
whom the real personal incentive is something much less 
or at all events, different. Many of these do their valuable 
work chiefly for the pleasure they take in the experimental 
technique : as, for instance, in the clean carrying-through of 
a chain of chemical operations, with pure, definite, and known 
substances at one end of the chain, and pure, definite, and 
new substances at the other; or again, in a systematic and 
highly accurate course of numerical measurements, made 
with apparatus calling for ingenuity in design and pure skill 
and precision in use, which shall describe some material or 
process more strictly than before. But Art for Art's sake is 
to us not an adequate justification for such labours; such 
arts, seductive as they are to every practitioner, beautiful as 
they most certainly are to the trained eye, must be Art for 
Science's sake. That is, for the sake of the further scrutiny 
and reflection which extract, from the products of the art, 
the aforesaid mental pictures. The accumulation of data is, 
for chemists, only the means to a verifiable picture. 

We have spoken of three objectives of chemical research; 


what are the other two? That which has just been described 
may be called the typical objective of a pure science. The 
other two, in varying degrees, are applications of chemical 
science to other things. Of them, some are illustrated under 
the titles already quoted from the "Annual Reports," and 
by the biochemical example already given. They are appli- 
cations of chemical science to other sciences, branches of 
learning. Needless to say, the services thus rendered to the 
sister-sciences are not by any means one-sided, and are re- 
paid at least in full. And finally, the application of chemistry 
to manufactures need only be mentioned to be appreciated. 
Most industrial processes depend upon chemical change, and 
their longevity (often their very birth as well) depends upon 
their being accurately understood. No stress has been here 
laid upon this aspect of chemistry, although it redounds to 
the very great benefit of chemical science itself as well as of 
industry, and although it is this aspect that is most com- 
monly hailed as the chief value of the science. But to say 
that the sanction for chemical research lies in its industrial 
applications is no more true than to say that the value of 
poetry is to be measured by the profits of its publishers and 
the employment which it gives to printers. The virtue of a 
great scientific research is the same as the virtue of a great 
poem; and its spirit is the same also. 

It remains only to add, in fulfilment of the plan of the 
essays in this volume, a note on a still wider theme. If the 
aim of philosophy is to determine the nature of ultimate 
reality, then I do not see how a chemist or, indeed, a prac- 
titioner of any of the natural sciences can indulge in philo- 
sophy except when he chooses to abrogate the principle by 
which he governs all his working life. In saying this I do 
not imply that such a bifurcation may not be allowable to 
him; indeed, in as much as he is human, he may not be able 
to avoid it; but I do wish to emphasize a fundamental dis- 
tinction between any science on the one hand and meta- 
physical philosophy on the other. 


The sciences aim at improving our understanding of the 
nature of Nature; and they are succeeding. But the absolute 
principle upon which is based all scientific work that has 
ever fulfilled this aim is, that no man can safely trust his 
cogitation about Nature. " Cogito, ergo sum," certainly; but 
the facile " Cogito, ergo est " is denied by science as having 
proved misleading, and is replaced by the humbler " Tango, 
ergo est." Scientific scepticism, the very root of scientific 
method, is not an axiom, not an article of faith; it is simply 
the austere wisdom born of millennia of experience. This 
experience has taught us uncompromisingly that human 
speculation about Nature, however lucidly expressed, how- 
ever palatable, will not stand the straightforward test of 
being used to control Nature, except on one condition. This 
condition is that speculation must reach out no farther than 
experiment and observation can follow it at once. Only by 
this modest restraint has it been possible for natural science 
to advance and to enlarge man's understanding of himself 
as a part of Creation. And the advance began only when 
men avowedly abandoned wide guessing for controlled guess- 
ing. " Hypotheses non fingo," said Newton I guess not at 


By A. S. EVE, D.Sc., F.R.S. 

Macdonald Professor of Physics, McGill University, Montreal 

A the present time all ideas are in a remarkable state 
of flux. 
The necessary revision of thought has to deal, in 
the first place, with those simple, elementary and funda- 
mental conceptions which underlie the whole structure of 
science, and, secondly, with that fascinating borderland where 
experiments and theory are combining to unlock the secrets 
of the unknown. 

In the effort to arrive at the plain truth a man endeavours 
to eliminate his individuality and to ascertain the behaviour 
of Nature apart from his own standpoint and mentality. In 
this undertaking he is often deluded into a false sense of 

As a necessary result of his upbringing in the realm of 
Nature, man has habits and ideas derived from his inherited 
characteristics, his environment, memory and the speeches 
and writings of his fellow-men. Illuminated by occasional 
flashes of genius he can produce something the existence of 
which was previously unknown. 

For example, man has invented a method of sending, from 
an aerial, continuous radio, or wireless, waves. The possi- 
bility of this feat is inherent in Nature, which permits electro- 
magnetic radiation with a stupendous scale of frequencies. 
Yet, so far as is known, continuous radio (wireless) waves of, 
let us say, 300 metres in length, and therefore a million cycles 
a second frequency, do not, in fact, exist in Nature unless 
they are man-made. So, too, it seems that man alone, for 
fairly obvious reasons, projects himself over the surface of 
the earth with the help of wheels. 


For the most part the Universe is a mirror wherein each 
man sees his own image, a reflection of his universal experi- 
ences. His own image is stamped on all that he would pass 
as true coinage, however honest his endeavours may be to 
eliminate himself and to abstract from all his experiences a 
clear vision of the whole. 

If he is a student of the physical world, he may test by 
experiment the theory of a common origin of phenomena, 
so that, as Bacon wrote: "He will receive, from what he 
sees passing on the earth, clear information concerning the 
nature of the celestial bodies, and, contrariwise from notions 
which he will discover in the heavens, will learn many 
particulars relating to the things below, which now lie con- 
cealed from us." This is an excellent forecast of the close 
and beneficial tie existing today between physics and astro- 

Faraday, crowned with the laurels of his victory in linking 
electricity with magnetism, electricity with chemistry, and 
optics with magnetism, pressed forward eagerly to combine 
electricity and gravitation. His experiments were not success- 
ful, yet he writes : " Here end my trials for the present, but 
they do not shake my strong feeling of the existence of a 
relation between gravity and electricity, though they give no 
proof that such a relation exists." 

This search for the simplification of a unified field which 
will include both gravitation and electricity has passed from 
laboratory experiment to the powerful mathematical analysis 
of such men as Einstein, Eddington and Weyl. Yet Faraday 
clearly foresaw a unity, now largely embodied in the estab- 
lished idea that the physical universe is a manifestation of 
energy in various forms, for he wrote : 

" I have long held the opinion, almost amounting to a con- 
viction, in common, I believe, with many other lovers of 
natural knowledge, that the various forms under which the 
forces of matter are made manifest have one common origin; 
or, in other words, are so directly related and mutually depen- 
dent that they are convertible, as it were, into one another, 
and possess equivalents of power in their action. In modern 


times the proofs of their convertibility have been accumu- 
lated to a very considerable extent, and a commencement 
made of their equivalent forces." 

This transmutability of energy, without loss of quantity, 
was well established long after Faraday wrote the above 
passage, so that to some extent the unity after which Faraday 
was striving has been achieved, and today we find matter 
and radiation, in forms kinetic or potential, all embraced in 
a single scheme under the Conservation of Energy, although 
the varied characters and forms of energy with their atten- 
dant " fields " will constantly form an endless subject for both 
discussion and research. 

It is not easy to summarize present ideas of the funda- 
mental notions and conceptions of science. There appear to 
be, on the one hand, observation, experiment, experience, 
perception, all imperfect; on the other hand, thought, im- 
agination, abstraction, reasoning, conception. From these 
imperfect parents arises a new offspring, a proposition, a con- 
clusion, a principle, a theory, something which is sometimes 
very improperly called a Law of Nature, for the idea is in the 
mind of man. If this new theory is expressed in analytical or 
mathematical form it may be subjected to most exacting 
tests namely, to co-ordinate the past events or to forecast 
the future. The new principle is frequently found to satisfy 
such keen tests. The reasoning which has followed from 
quite imperfect experiments is discovered to have a close fit 
with natural phenomena past, present and future. We con- 
clude not only that our reasoning faculties are trustworthy, 
but that there is an orderly process or habit in Nature which 
permits us to assume that under similar circumstances similar 
results will probably recur, in spite of the fact that no two 
events can be identical, differing as they must needs do in 
time, or in place, or, more commonly, in both. 

Thus Newton was greatly impressed by the experiments 
and laws of Galilei, by his own experiment on water in a 
rotating bucket suspended by a rope, and by the experiments 
on the collision between two elastic balls of unequal sizes 
suspended side by side with separate strings : 


" Sir Christopher Wren, Dr. Wallis and Mr. Huygens, the 
greatest geometers of our times, did severally determine the 
rules of the congress and reflexion of hard bodies, and much 
about the same time communicated their discoveries to the 
Royal Society, exactly agreeing among themselves as to those 
rules/' Newton repeated these experiments, making careful 
corrections for the resistance of the air. He found that 
"Action and Reaction were equal and opposite," so that the 
momentum (mass x velocity) lost by the one body was exactly 
gained by the other. On so slender a base of experiment was 
built the philosophy of the Principia, with its concise mathe- 
matical reasoning, and yet the entire scheme was successfully 
extended to the whole solar system, to planets, moons, comets 
and tides, satisfying the observation of Tycho Brahe and the 
orbital laws deduced therefrom by Kepler. 

Truly we may repeat with Boole : 

"The domain of reason is thus revealed to us as larger 
than that of imagination/' 

Electrical engineers are in general ingenious and some- 
what matter-of-fact men who generate or separate and trans- 
mit electricity or "juice" with complete success, not greatly 
worried by Maxwell's equations or modern atomic physics. 
Curiously enough they use frequently in their calculations 
about alternating currents the imaginary, or impossible, 
square root of minus one, and the symbol employed (j), 
denoting \/ i , disappears from their final results, which 
are, of course, in agreement with future experience. 

A great hydro-electric scheme may be devised, the head 
and supply of water calculated, dams constructed, power- 
house, turbines and generators planned, made and installed, 
distribution lines and transformers erected, and when the 
power is " turned on " everything works according to plan. A 
gigantic experiment in applied mathematical-physics, which 
today, owing to familiarity, causes little surprise! Noting, 
then, these great achievements of mathematics, physics, 
chemistry and engineering, it is pertinent to inquire whether 
the same methods might not be extended successfully to 
other fields biological, moral and spiritual. Whether some 


abstractions may be made from past and present experience 
which will fit closely with future development. 

In most cases the number and variety of variables leave 
small hope of any approach to mathematical treatment. Yet 
it is fair to state that all the greatest moral leaders, teachers 
and thinkers have indeed followed that very path of abstrac- 
tion from experience towards great principles which are in 
harmony with universal truths, and where the whole revela- 
tion is far wider and deeper than are the initial data. So that 
the fountain certainly rises higher than the apparent source. 

What is that source? The late Lord Rayleigh once in- 
quired, supposing that he discovered a really new theorem 
previously unknown to man, whether that theorem had never 
existed in any mind before. " To me," he said, " that seems 
unthinkable ! " 

What is that source? 

"Mathematical notation is not a mere mechanism for 
calculating numbers, but the supporting framework of the 
organic relation of man's mind to the as yet unknown of 
which religions are the outward expression " (Mary Everest 

What is that source? 

" The most exhausting of all our adventures is that journey 
down the long corridors of the mind to the last hall where 
belief is enthroned." 

It is an interesting but rather futile speculation to inquire 
as to what would be our present or future state of knowledge 
if the earth were covered everywhere with so dense an en- 
velope of cloud that no rift permitted even a passing glimpse 
of sun, moon, planets or stars; whether the changes of length 
of day and night in different seasons and various latitudes 
would have permitted philosophers to infer a light-giving sun; 
whether the spheroidal shape of the earth, the gyroscope, and 
the famous Foucault pendulum experiment would have 
jointly suggested the rotation of the earth! And, if so, with 
reference to what exterior and unknown body or bodies, or 
what imaginary system of axes? It is useless to inquire; and 
according to Silberstein the question would have no meaning, 


though he might himself indeed have been one of many who 
would have indulged in some such speculation. The history 
of science does record many similar inferences, which enter, 
rightly or wrongly, into the more speculative domains of 
physical science, even down to the present day. 

Every physicist believes and must believe that there is 
something " in being" from which " messages" arrive to him 
by sight, sound or feeling, either directly, as by the eye, or 
indirectly as by photograph, which messages he can some- 
times arrange and interpret so as to obtain so-called " laws " 
of Nature. 1 These laws are made by man, but the possibility 
of making them is a common experience of most men, and 
are presumably in Nature herself. These " laws " may there- 
fore in an indirect and improper sense be transferred from 
man to Nature. The " laws " are summarised by man from 
past experiences, and they can frequently be used to predict 
probable future events e.g., an eclipse. They must never be 
regarded as fixed, certain, inevitable or immutable laws : 

" Laws state what has been, and what may be expected to 
be; not what will always be, or what must be " (Tennant). 

Hence Science cannot have dogmas or creeds, but only 
expectations of the future founded on the past; but there is 
an extraordinary weight of evidence of the permanence of 
the predictability of Nature, which increased knowledge in- 
tensifies. Hence, the man of Science is justified in combating 
superstitions founded on insufficient evidence or irrational 
thought, but he can never hope to fight successfully those 
experiences which are not the common property of a large 
number of experienced observers. Hence the troubles relative 
to divining-rods, telepathy, ectoplasm, second sight, magic, 
miracles and mediums generally. The proof of fraud in one 
cAse cannot involve the proof of fraud in all cases. Here 
psychology is so mixed with physics that the pure physicist 
is like a little child before a skilful conjuror, and it is a law 

1 In spite of McTaggart, " The existence of matter is a bare pos- 
sibility to which it would be foolish to attach the least importance." 
And of Ward, " As to ontal Nature we know nothing and can pre- 
dict nothing, save with futility." 


of conjurors that any required number of white rabbits can 
be extracted from a top-hat. On the other hand, there is a 
mass of evidence that rabbits do not normally enter the world 
in that manner. 

In Physics, Nature is quite the gentleman and always plays 
the game. Whether white light passes through a glass prism 
or breaks up in raindrops to form a rainbow, the order of the 
colours is maintained and can be well " explained " by the 
simple laws of refraction in glass or water respectively. The 
next step is the " explanation " of the dispersion of light by 
the medium in terms of molecules, and this is referred to the 
scattering of light by electrons and protons either on classical 
or wave-mechanical principles. A further step has to deal 
with the constitution of electrons and their reaction with the 
so-called electrical "field." It is obvious that the chain of 
explanations can never end, so that Physics is and must 
remain inexhaustible in content. To the ordinary man these 
successive steps seem more like a retreat from the field than 
an advance on the citadel. Such chains of inquiries, criticisms 
and explanations are, however, inevitable in every healthy 
stage of scientific endeavour. 

The methods of science are founded on observation and 
experiments, guided by reason and wisdom, and justified by 
success. The ultimate, or " ontal " (things that be), is always 
evasive and can be but partially inferred at the best, for the 
same phenomena can often be accounted for by more than 
one speculative entity. " Hence Hamilton was led to main- 
tain that we have no absolute or pure knowledge of anything, 
and no knowledge at all of the absolute or ontal "; but 
Tennant judiciously adds that " our knowledge is relevant to 
Reality, while its impurity is an irrelevancy/' And again : 
"Our laws of Nature are in some measure laws as to our 
thinking, as well as laws to the ontal; that is partly why simi- 
larities exist between equations belonging to different depart- 
ments of physics, in spite of profound differences between the 
phenomena of which they obtain, so that things, of their own 
behaviour, make their laws, and 'obey' them by making 
them with persistent regularity." 


The bells in the belfry are moved by ropes, and presum- 
ably know nothing and obey nothing, nor do they compre- 
hend the ringers at the other end of the ropes. Tne ringers 
in the lower floor of the tower may also be in ignorance of the 
nature of the bells and the mechanical contrivances for sup- 
porting and swinging them, and yet the ringers may produce 
excellent chimes. Indeed, many great composers and 
musicians have been completely ignorant of mechanics, 
acoustics, and all branches of physics. We are the ringers of 
bells, and we can never be sure of the nature of the unvisited 
belfry whence come the wonderful chimes. We seem, how- 
ever, to possess the too often abused power of " pulling the 


No future event is more than probable, although it must 
be admitted that a mixture of oxygen and hydrogen is ex- 
ceedingly apt to lead to a dangerous explosion when the 
smallest electric spark is passed through any part of the gas. 
The practical and common-sense man would say that such an 
explosion is certain, but if the gases are sufficiently dry, if 
nearly all water-vapour is abstracted, an explosion will not 
occur. There must be a trace of water-vapour to act as 
catalyst 1 and to produce the catastrophe. So, too, the change 
of a switch at a railway, though but a few inches, may decide 
whether a train shall go to Moscow or to Rome, and a trifling 
experience in a man's career may project him towards 
Fascism, Bolshevism or any other of the growing class of 

Some of the apparent uniformity of Nature is carried down 
to fundamental concepts. Thus W. E. Johnson claims that 
" every specimen of argon has the same atomic weight; this 
specimen has the atomic weight 39-9; therefore every speci- 
men has the atomic weight 39*9." This reads well and looks 

1 Catalyst, a " loosener up," a very useful word to disguise our 
ignorance of the great influence of small causes in physics and 
chemistry. However, " catalytic substances are those wnicn modify 
the rapidity of a definite chemical reaction without changing their 
own content of energy." So that " within the strict province of the 
law of energy there still remains room for the greatest variation in 
the temporal extent of the phenomenon." (W. Ostwald.) 


well, but it need not be true ! It has been shown by Aston, at 
the Cavendish Laboratory, that argon consists ot a mixture 
of at least two kinds of argons, whose atomic weights are 40 
and 36. These two types of argons are isotopes, and occupy 
the same place in the periodic table. Their outer constitu- 
tions are very similar because the satellite electrons are 
identical in number and alike in arrangement. Hence these 
isotopes are non-separable by chemical methods, but they 
may be separated with difficulty and in small quantities by 
physical methods, so that the above quotation, which looks 
safe enough, is not in fact dependable. The statement might, 
however, be revised to read: " Every specimen of argon has 
the same atomic number 18, because every atom of argon has 
atomic number 18." This change in viewpoint involves a 
great discovery, with a notable advance in knowledge and 
simplicity. Atomic weight, or mass, is mainly governed by 
the number of protons in the nucleus, while atomic number 
has to do with electric charge, or the excess of protons over 
electrons in the nucleus. Argon alone of the elements has 
atomic number 18, while some calcium and argon atoms each 
have atomic mass 40, and may, in that case, be " isobares," 
or different elements with equal atomic weights or mass. 

It is noteworthy that physicists in all parts of the world 
taking any specimen of iron, and using any good spectro- 
scope, agree with one another in the main as to the wave- 
length and frequency of the many thousands of lines in the 
iron spectrum. These lines are due to the "messages" from the 
iron atoms when disturbed in an arc or spark due to a current 
of electricity passing through a small gap between two pieces 
of iron. It is perhaps possible, but certainly difficult, to infer 
the mechanism of the oscillating electrons. It may well be 
that several different models or schemes or mathematical 
formulas would account for the same messages. A good 
cuckoo clock may sometimes fool you into the belief that an 
early messenger of spring has arrived in the land! Any 
scheme will be acclaimed as satisfactory which will give a good 
account of the spectrum of iron, and also of other metals, such 
as tin, lead, mercury, silver and the like. The inquiry would 


then be enlarged in order to ascertain whether the " explana- 
tion " can be extended to apply to other phenomena such as 
the valency bonds which link atoms together into molecules. 

There can be no intellectual satisfaction if the physical 
chemist arrives at one model of the atom and the spectro- 
scopist to a wholly different and inconsistent scheme. Such a 
state of affairs is not at all imaginary. Not long ago discussion 
was rife as to the rival merits of the Langmuir static atoms 
and the Bohr dynamic atoms. These both have served, or are 
serving, a useful function; they arc some sort of approxima- 
tions to the " real " atoms, all messages from which we strive 
to interpret correctly. 

It is remarkable, and somewhat puzzling to physicists, why 
some philosophers and others appear to attach so much im- 
portance to those " messages " which are seen by the eye or 
heard by the ear. The "existence" of many stars, never 
actually seen, or likely to be seen, is inferred from photo- 
graphic plates exposed in the field of a good telescope for a 
long period of time. These stars have as much claim to recog- 
nition as those seen directly by the eye. It is true that their 
position on the plates is usually determined by the eye, but 
with the help of a source of light, a photo-electric cell and an 
amplifier it would be quite possible to ring an electric bell so 
as to reveal the position of each star, both on the photographic 
plate and in the heavens; and in that case the messages from 
the invisible stars could be appreciated by the ears of men 
totally blind. 

Seeing and hearing are specially and highly organised 
methods of feeling, and the old adage " Seeing is believing " 
should be changed to " Feeling is believing," and even that 
saying should be confined to belief in the feeling until other 
evidence is forthcoming. 

In the above discussion nothing has been said of the trans- 
fer of the messages from eye, ear or surface of the body along 
the nerves to the suitable region of the brain. The importance 
of these transfers cannot be over-estimated, particularly be- 
cause when in good health we are entirely unconscious of the 
whole process. We enter here into the domains of the physio- 


legist and psychologist, each successive stage f involving greater 
difficulties. It is scarcely possible to imagine that the transfer 
of a purely physical message of light of a given wavelength 
into the psychical appreciation of a given related colour can 
ever be approximately explained, whatever the character of 
the intermediate physiological processes might be. 

There is a further point which is a puzzle to physicists, 
this time in the domain of biology namely, the frequent use 
of the word " function." Certainly the function of the eye is to 
see, of the ear to hear, and of the heart to force rhythmically 
the blood supply through the arteries. These organs have 
been developed for a purpose; for what purpose is often 
obvious; by whose purpose is obscure. 

No doubt the function of a galvanometer is to measure 
current and of a thermometer to indicate temperature; these 
instruments were constructed and calibrated by deliberate 
human design for concise purposes. Writers on physics, how- 
ever, rarely, if ever, make use of the term " function " in the 
manner of the biologists. We have to conclude that the word 
" function " either indicates a purpose with a definite design 
or, excluding such assumptions, we may attempt an explana- 
tion on the basis of trial and error, with more or less prompt 
elimination of failures. In that case, what is the use, let us 
ask, of a half-evolved and imperfect semicircular canal with 
a view to guiding the equilibrium of a body? 

It may be that " the sting of Darwinism rather lay in the 
suggestion that proximate and 'mechanical' causes were 
sufficient to produce the adaptation from which the teleology 
of the eighteenth century had argued to God "... so that 
" the discovery of organic evolution has caused the teleologist 
to shift his ground from special designs in the products to 
directivity in the process and plan in the primary colloca- 
tions " (Tennant). 

If that is so, then there may perhaps be a general Cosmic 
End, or Purpose as a whole, of which there is no certain evi- 
dence in the parts; unless the entire mechanistic plan is itself 
the indication of an omnipresent purpose. Certainly no 
account of the Universe is complete which does not give 


adequate reasons for the highest qualities of man, and those 
for the present, and probably for all time, are definitely out- 
side and beyond the range of any type of exact science. 

Some may prefer to discard the whole preceding suggestion 
and regard Nature as the inevitable outcome of chance hap- 
penings, to advocate the evolution of man from inert matter 
through simple cells and a chain of creatures up to his present 
physical and mental development. We are thus asked to 
accept the most stupendous chance and the highest improb- 
ability, a miracle greater than any that has ever been con- 
ceived. A miracle that has not only occurred in the past, but 
moreover persists in occurring before our very eyes, here, 
now ! Indeed, there may be no need to consider the remote 
changes, but let the case rest on the stages from conception 
to birth. Familiar happenings such as the hatching of chicks 
from eggs can be traced, step by step, and experiments in- 
volving modifications can be made, but that the whole pro- 
ceedings in any way resemble the manufacture of a locomo- 
tive engine is palpably absurd and advocated by none. It is 
not difficult to trace the development of the foot from the 
"dawn horse" to the latest Derby winner, but none can 
guess the process forwards to the horse or horses of a million 
years hence. By careful breeding and selection it might be 
possible to reverse the process and to devolve, or revolve, to 
the five-toed horse. Yet this, too, would be an evolution, for 
that which happens with advance of time, whether we deem 
it good or bad, progress or regress, must inevitably be evo- 

There are, however, still a few who carry forward into all 
realms such conceptions of exactitude as are associated with 
solar systems, Ford cars, moving pictures and so forth, and 
their only insufficient plea is the pertinent question, " What 
else can we do?" No series of successful applications of this 
method can ever succeed in proving that the mechanistic 
theory in any degree represents the entire situation. 

We have climbed to our present state of knowledge on the 
backs of a few giants ! Notable is the early contribution on 
the magnet by Gilbert, Physician to Queen Elizabeth, a defi- 


nite scientific achievement predating the work of Galilei, 
Kepler and Descartes. The reference of Nature to experi- 
ment and reason, as opposed to speculation and authority, 
was the work of Galilei, while the full blaze of real physics 
burnt forth with Newton, who revealed the calculable order- 
liness of the solar system, to which the most highly organised 
railway system can never hope to attain. The younger science 
of Electricity began its brilliant career early in the eighteenth 
century with Galvani, Volta, Oersted ana Ampere, but the 
experimental researches of Faraday and the mathematical 
genius of Maxwell have enabled electricity to outstrip and 
even sometimes to supplant the older science of dynamics. 
Hertz was able to discover the wireless waves which Max- 
well's equations inferred, while towards the other end of the 
great electromagnetic system Rontgen produced the short 
waves which are able to penetrate considerable thicknesses of 
all material bodies. Improved technique in obtaining high 
vacua had already enabled Crookes to discover cathode rays, 
which he surmised to be " matter in the fourth state," which 
J. J. Thomson proved to consist of swift-moving corpuscles, 
or electrons, now known not so much as matter in a new 
state, but rather as one of the main fundamental consti- 
tuents of all the atoms of all the elements. 1 

Four years before the close of the nineteenth century 
H. Becquerel discovered the radioactive property of the atoms 
of the heaviest element, uranium. There followed in rapid 
succession the discovery of polonium and radium by Madame 

1 The pastime of atom building has developed new interest now 
that the iundamental building blocks have advanced in number to 

Name. Charge. Relative Mass. 

Electron -e l l l %45 

Positron -fe 1/1845 (?) 

Proton -fe i 

Neutron o i 

Deutron -fe 2 

Alpha particle ... -f 2e 4 

The last two can be built from protons and neutrons however. 



Curie, the theory of radioactive change by Rutherford and 
Soddy, and the unveiling of the periods and properties of 
more than forty different elements which spontaneously dis- 
integrate and transmute according to a simple and rigorous 
law or rule. It is memorable that the Theory of Radioactive 
Change was deduced from experiments on only two sub- 
stances, Thorium X and Uranium X, that it was developed 
in Rutherford's Bakerian Lecture, and that it has since been 
found to hold rigorously for all radioactive elements. 

The twentieth century opened with the discovery by 
Planck of the atomicity of action and the quantum nature of 
radiation. Energy exchange between atoms takes place in 
bundles strictly proportional to the frequency of the electro- 
magnetic waves. It is remarkable that investigation of the 
energy distribution in the spectrum of radiation from hot 
bodies, a statistical effect, revealed at the same time the values 
of Planck's constant, h, and of the electronic charge, e, within 
a small percentage of the best experimental values since ob- 
tained by a variety of other methods. It might perhaps be 
expected that these small values would be " smoothed out " 
in any experiments dealing with the great concourse of atoms, 
and it is significant that the facts are otherwise. 

Philosophers sometimes complain that physicists are con- 
stantly changing their viewpoint. In the very forefront of 
discovery this is indeed true, and such fluidity of thought is 
a most desirable asset, to be envied by theologians, politicians, 
economists and others. Behind all these vanguards of thought 
there is a great body of solid and permanent achievement, 
among which Planck's work will ever hold a leading place. 

Rutherford's experiments with thin metal foils bombarded 
by the alpha particles from radium definitely established the 
existence of a small central nucleus in every atom where the 
preponderating bulk of the mass of the atom was concen- 
trated, so that it was proved that all matter was by no means 
continuous but " full of holes." 

Moseley exposed a number of substances, consecutive in 
the periodic table of elements, to the action of Rontgen rays, 
and the characteristic radiations, after reflection from a 


crystal surface, were dispersed so as to indicate the natural 
periods of the higher frequencies. It was possible to demon- 
strate that the atomic number could be definitely identified 
with the number of positive unitary charges of the nucleus. 

Bohr linked the measured frequency of radiation from 
atoms with the orbital satellites round the Rutherfordian 
nucleus, 1 intimately connecting in numerical agreement the 
frequency, Planck's constant, Moseley's atomic number, and 
the electronic mass and charge. The dynamical assumptions 
could not be rationally upheld, but in the case of the simpler 
atoms the verifications were so conclusive that the achieve- 
ment was Newtonian in splendour. There followed the ejec- 
tion of protons from the lighter elements by bombardment 
with alpha particle, and the designed transmutation of ele- 
ments when the alpha particle remained in the nucleus, and 
a proton was displaced, thereby producing a definite change 
both of atomic number and of atomic mass, by Rutherford, 
Blackett and others. 

The recent discovery by Lord Rutherford and his co- 
workers, Dr. Cockcroft and Dr. Walton, is specially note- 
worthy. Occasionally a proton, urged to a high velocity with 
a few hundred kilovolts, enters into partnership with the 
nucleus of lithium with its seven protons and three electrons, 
and the combination apparently splits into two alpha 
particles, which on loss of velocity acquire electrons and 
become two helium atoms. Thus hydrogen and lithium in a 
sense physical, and not chemical, give rise to helium. 

The Rutherford-Bohr theory of the atom has indeed stimu- 
lated research and has been extraordinarily fruitful in 
problems relating to the nucleus of atoms. Meanwhile the 
theory guided research students through successive stages in 
the unravelling of the tangled skein of the spectral lines of 
the various elements, but successive and increasing difficulties 

1 The quantum of radiant energy (Planck's constant multiplied 
by the frequency) from an atom is equal to the energy released by 
a definite change of " level " by the orbital electron. This general- 
ization due to Bohr is quite fundamental, and is closely akin to 
Einstein's photoelectric relation. 


arose until about 1925 it became apparent that the whole 
scheme was but an approximation to something far more 
subtle and exacting. 

A new outburst of what might perhaps be called modern- 
istic, or ultra-modern, physics sprang; rapidly into being. It 

i i r IT i- i 

is too early to estimate the tull potentiality or ultimate suc- 
cess of this great movement. It must suffice to indicate its 
character and scope. The principal actors in the new drama 
of modern physics are notably young men Heisenberg, de 
Broglie, Dirac, Schrodinger though the comparatively 
veteran Bohr has often been leader or pilot. 

It was Heisenberg who first broke away from the now 
old quantum mechanics and, ignoring models and orbits, 
focussed his attention on a scheme of mathematics which 
would portray as accurately as possible the essentially observ- 
able and measurable results of spectroscopy. It must again 
be urged that the lines of a spectrum on a photographic plate 
indicate frequencies of vibration, originating presumably in 
the atom, and indicating some vibrational changes of an 
abrupt or oscillatory character, from which the nature of the 
atom may be inferred. Heisenberg concentrated his attention 
on these measured " messages " rather than on the constitu- 
tion of the atom itself, which might have an indefinite 
number of possible mechanisms satisfying the data. Heisen- 
berg, Born and others set forth in an array, or matrix, the set 
of all possible oscillations involving both frequency and 
amplitude, still using the fundamental principle that the 
radiation quantum is equal to the energy change of the 
electron in the atom. They then proceeded to deduce rules 
which would account for the amplitude and intensity. Defi- 
nite calculations with reference to the spectra of hydrogen 
and helium showed a fruitful crop of verifications with the 
more fundamental views usually identified with electronic 

So long as the electron was regarded as merely a small 
spherical entity of the type of electricity designated most 
unfortunately as "negative," it could be stated that every 
electron was like every other electron, so that if two of them 


exchanged places in an atom or molecule no experiment 
could possibly detect any resulting difference. 

Spectroscopic analysis, however, indicates that there is a 
fundamental difference between electrons and that this could 
be accounted for by the conception of a spin. A rotating 
electrical charge resembles a current and gives rise to mag- 
netism, so that one end of a spinning electron is a north pole, 
the other end a south pole. Two electrons in proximity, with 
their corresponding poles close together, would react with a 
repulsive force, but, if their opposite poles were near one 
another there would be an attraction. An electron has today 
so unlocalised a character that perhaps a quasi-spin would be 
a better term to indicate the phenomenon in question. Just 
as two pendulous bodies attached to a horizontal cord can 
swing to and fro either together or in opposition, so electrons 
in an atom can be arranged to be symmetric or antisym- 
metric, and whichever arrangement exists also persists. We 
can therefore ask with great wonderment why the " choice " 
was made in favour of the antisymmetric! To quote 
Darwin : 1 

" Our principle then suggests that it is natural to suppose 
that the world is either wholly symmetric or wholly anti- 
symmetric, but it provides not the slightest hint of which. 
As far as we may judge, worlds would be quite possible of 
either kind, but here the Exclusion Principle steps in and 
gives a definite ruling. The world was created antisym- 

In terms of the hypothetical electrons of the atom the 
fundamental rules of the atomic game seem to be : 

(1) The identity of an electron in any atom is fully secured 
by four whole or "quantum" numbers. (These numbers 
when multiplied by h/m are, or have the character of, 
angular momenta.) 

(2) No two electrons in an atom ever have the same labels 
or four quantum numbers (Pauli's exclusion principle). 

(3) An electron is never observable in exact position when 

1 The New Conceptions of Matter, C. G. Darwin (G. Bell and 
Sons), 1931. 


its velocity is khown; and a knowledge of its position forbids 
a knowledge of its exact velocity (Heisenberg's uncertainty 
principle). This veto appears not to be due to the stupidity 
of the observer, but to be an intrinsic limitation due to the 
fact that h (Planck's constant) designates a lower limit to the 
value of action, so that further subdivision, as in the case of 
the electronic charge, does not or cannot occur. 

Some philosophers seem to imagine that physicists conjure 
up these rather mad ideas of their own free will out of 
their fertile imaginations. Not so! They are thrust upon 
them by the stern facts of Nature, and the ideas only 
seem strange because they are unfamiliar. "Nature will 
open to the right pass-word, but she has chosen it, not we " 

Working on parallel lines, Dirac at Cambridge indepen- 
dently evolved a most powerful super-algebra to deal with the 
same problems. Einstein's praise and criticism may be 
quoted : 

"The latest and most successful creation of theoretical 
physics namely, Quantum Mechanics is fundamentally 
different in its principles from the two programmes which we 
will briefly call Newton's and Maxwell's. For the quantities 
that appear in its laws make no claim to describe Physical 
Reality itself, but only the probability of the appearance of a 
particular physical reality on which our attention is fixed. 
Dirac, to whom, in my opinion, we owe the most logically 
perfect presentation of this theory, rightly points out that it 
appears, for example, to be by no means easy to give a theo- 
retical description of a photon that shall contain within it the 
reasons that determine whether or not the photon will pass a 
polariser set obliquely to its path/' 

This last point is not, however, to ordinary mortals the 
main difficulty, for Dirac's faultless logic and cold symbolism 
leave many readers in extreme doubt as to the nature and 
properties of the subjects or objects under discussion. The 
blame for this should not, however, necessarily be assigned 
to Dirac ! 

In the above quotation Einstein uses the word " photon " 


expressive of his own theory of photo-electricity namely, 
that light travels as a quantum from one atom to another 
atom, notwithstanding the wave theory of light so indispens- 
able to the well-established interference of light. This dual 
character of radiation, involving spreading waves from a 
source, and at the same time the collected energy of a bundle, 
involves a definite contradiction which has been accepted 
rather than explained ! 

The French physicist de Broglie had in the meanwhile 
blazed a new trail ! Guided by the beacon lights of Hamil- 
ton's work on Stationary Action, he saw that the paths of 
particles and the paths of waves might and should, under 
suitable circumstances, be identical. This was the first step 
towards wave-mechanics. In tracing light through a system 
of lenses, as with a telescope, it is often sufficient to speak of 
rays of light passing along straight lines. So, too, it is possible 
to give a fair description of a rainbow by the refraction and 
reflection of rays of light in the raindrops; but when the 
primary bow is doubled or trebled it is clear that geometrical 
optics is not sufficient, and it is necessary to pass to physical 
optics and to employ a wave theory. De Broglie realised that 
electron particles were essentially too crude, and that small 
waves, or rather groups of waves (wave packets, as they are 
called), could wheel round the nucleus of the atom, thus 
forming standing waves with an integral number of nodes. 
This idea of de Broglie was quickly seized and greatly ex- 
tended by Schrodinger, who obtained suitable equations 
eliminating the time factor, and arrived at results well sup- 
ported by experimental evidence, indicating the probable 
rather than the necessary position of the shifting electrons. 
To the mathematician Mott's Wave Mechanics may be 
recommended, and to others a brave attempt at explanation 
has been made in C. G. Darwin's New Conceptions of Matter, 
of which it may be said that, from the nature of the subject, 
the success is necessarily partial, that the account could not 
have been a better one, and the wonder is that it could be 
done at all ! 

In the first place, it is natural to inquire, with respect to the 


de Broglie waves, "What is the nature of the medium in 
which the waves occur?" It is safe to reply, "Certainly not 
the aether." In the case of light-waves, which appear to travel 
at 186,000 miles a second through a vacuum, the answer may 
perhaps be the aether, whatever that shadowy conception may 
or may not involve. In the case of the de Broglie waves, how- 
ever, a velocity is involved which is greater than the velocity 
of light. This is sometimes spoken or as a phase-velocity, and 
the velocity of a group of such phase-waves is the observed 
and measured velocity of any particle. It is perhaps more 
correct to state that in the case of the de Broglie waves there 
is no medium at all, although the transformation equation of 
Einstein's special relativity theory clearly points to the exist- 
ence of a velocity. 1 Indeed, Mott, writing on this matter, and 
referring to Schrodinger's wave equation, states : 

"The wave function is just a convenient shorthand. The 
waves are not waves in any medium. There are no waves 
accompanying an electron, until we have observed the elec- 
tron. Then we make use of the wave representation to em- 
body the results of our observations. The wave equation tells 
us what may be deduced from our observations, about the 
future position and velocity of an electron/' 

This hardly suggests a final position to be occupied by 
physicists, but rather a point d'appui to be consolidated for a 
further advance. Rather it may be asked why physicists have 
permitted themselves to be manoeuvred into a position so 
dangerous and vulnerable. The answer is twofold. In the 
first place, it became necessary to abandon the definite Bohr 
orbits for the electrons moving as satellites round the Ruther- 

1 The time and space transformation equation in question is 


and here is indication of a velocity u~ where v may be the 

velocity of a particle, which can be proved to be the group velocity 
of u. 


ford nucleus cff the atom. These orbits gave a valuable first 
approximation to the facts, but they could not stand the 
tests of experiments, so that some modifications, whether of 
Heisenberg, or de Broglie, or Schrodinger were essential. In 
the second place, the wonderful experiments of Davisson and 
Germer, and of G. P. Thomson, definitely proved that elec- 
trons had not merely the attributes of charged particles, be- 
cause a narrow beam of electrons fired through exceedingly 
thin sheets of aluminium or gold foil gave interference 
patterns strongly resembling those due to Rontgen rays under 
somewhat similar conditions, but with this notable and funda- 
mental difference, that the Rontgen rays and their patterns 
cannot be deflected by a magnet, while the electrons and their 
patterns can be readily shifted en bloc by a magnetic field 
from one position to another, indicating that photons have 
no electrical charge, while electrons have a "negative" charge, 
negative merely being a description of the type of charge and 
not a minus quantity. In fact, two definite conclusions are 
forced upon us. The photo-electric effect that is, the ejection 
of electrons from atoms by light indicates that a " particle " 
scheme is necessary as well as a " wave " scheme for light. 
The word " photon " is used to denote that which has this 
dual nature. On the other hand, the experiments just 
described show that an electron is not merely a charged 
particle, as formerly supposed, but it has also something of 
the nature of waves. 1 The universe seems to be built of 
particles that are wavicles and wavicles that are particles. The 
physicist has three 2 entities to play with electrons, protons 
and photons with their attendant " fields." The characters 
in the drama are somewhat difficult to control, as they are 
constantly changing their roles from Mr. Hyde to Dr. Jekyll. 
Most of these remarkable properties have been established 
rather than explained, and it is impossible to guess whether 

1 The photon has energy equal to Planck's constant multiplied by 
the frequency, and the electron has a wave-length ecjual to Planck's 
constant divided by its momentum. A remarkably simple and well- 
established result. 

2 See, however, footnote p. 225. 


an explanation may ever be forthcoming or whether we are 
at last driven to the " nature of things ! " 

For example, in the famous wave-equation which Schro- 
dinger so effectively uses there is a characteristic function of 
that which waves, denoted by the Greek letter \Jj (psi). What 
does this stand for? Jeans gives the answer: 

" Most of the symbols used by the mathematical physicists 
today convey no physical picture to his mind; he can explain 
and predict the whole course of atomic structure in terms of 
the behaviour of a symbol the \jj of Schrodineer's wave- 
mechanics but he cannot tell us what i// means in physics; 
and I for one doubt if he will ever be able to do so." 

A most unsatisfactory state of affairs ! Yet, as Mott states, 
as far as " atomic fields are concerned the predictions made 
by the wave-mechanics are in accordance with experiment, 
so far as is known at the present time." And again, to quote 
Darwin : 

" It is one of the most unsatisfactory features of the enor- 
mous recent developments of science that they are so remote 
from all the ordinary things of life." 

Thus, for example, if a beam of electrons is fired at two small 
holes, made close together through a screen, there will be an 
interference pattern of light and shade on the receiving 
photographic plate, placed behind the screen, and Darwin 
states : " The only possible way of explaining this is to say 
that each of the electrons knows all about both holes, or has 
gone through both holes at the same time, because only then 
could we get the cancelling effect characteristic of interfer- 
ence. This is the direct inference from our experiment, and 
there is no escape from it. It is so contrary to all our ordinary 
ideas about matter that it must be regarded as the greatest 
revolution that has happened in the whole of physical 

If an electron has to be represented by a little packet or 
bundle of waves, we may well ask at what point in the bundle 
is the mass, and where and what is the negative electric 
charge? No suggestion has been made as to the nature or posi- 
tion of the electricity as apart from the mass, and the answer 


seems to be, in this case and in all cases, that it is impossible 
to state where the electron is; all that can be said is that the 
most probable position of the electron is wherever the waves 
have the greatest amplitude, where the storm waves are 
highest, as it were. Indeed, intensity and probability seem to 
be reversible terms. 

The wave-mechanics gives an explanation, and indeed the 
only explanation, of the remarkable properties of radioactive 
bodies. A uranium atom " spontaneously " breaks up on the 
average once in a thousand million years when an alpha 
particle escapes from its electrical captivity in the nucleus. 
On the other hand, a quick-change atom effects a similar 
ejection in about a millionth of a second. It appears that the 
alpha particle is also a wave group or wavicle, and while a real 
particle never could escape from its captivity in the nucleus, 
there is a probability of escape for the alpha wave-particle; 
this probability is indeed calculable, and there is a satisfactory 
relation, verifiable by experiment, between the velocity of the 
ejected alpha particle and the average time of imprisonment 
in the nucleus. 

Far less satisfactory to a physicist, however pleasing to the 
mathematician, is the fact that for the description of even 
two electrons circling round outside the nucleus of an atom it 
is necessary to use six dimensions to obtain even the proba- 
bility of their position. I can do no better than quote Darwin 

"We have seen that many of the characters of an electron 
can be represented by regarding it as a wave-group moving 
about in space. It would be tempting then to suppose that, 
when there are two electrons, there are two wave-groups both 
moving about in space. But this will not do, since two wave- 
groups are simply a single more complicated wave-group, 
whereas two electrons are radically different from one. For 
the correct treatment of the waves of two electrons it is 
necessary to have two spaces, or in the language used by 
mathematicians, a space of six dimensions. Of course, there 
are not really six dimensions, but the mathematician finds it 
convenient to think and speak in that way. The best picture 


we can make for ordinary use is something like this. We can 
make a diagrammatic representation of the wave of an elec- 
tron by sketching a wave-group on a sheet of paper. It is true 
this is only in two dimensions, but it is comparatively easy 
for us to understand three dimensions when we have mastered 
two. The behaviour of two electrons is described, not by two 
wave-groups on the paper, but by having two sheets of paper 
each with one group on it. The second sheet overlies the first. 
As the motion goes on, each smudge moves about in its own 
sheet and no transfer from one to the other is allowed. 
Nevertheless, the ink of each group can, so to speak, see what 
the other one is doing, and experiences a force from it. Since 
there is repulsion between two electrons, we can say that the 
patches try to avoid one another. On the other hand, there is 
attraction between an electron and a proton, and so in that 
case the two patches tend to come together. This description 
of the behaviour of two particles applies in cases where they 
do not approach very closely to one another, but we are going 
to meet cases where things are not so simple, and where the 
six dimensions cannot be divided into a pair of threes. I am 
involved in the difficulty of having to explain ideas which are 
mathematically fairly easy in terms of the geometry of several 
dimensions, but which it is by no means easy to apprehend 

Enough has now been said to whet the appetite of the 
reader for more information. The Universe is far stranger 
than any of us foresaw. To avoid the metaphysics of " ideas 
not essentially observable " we have certainly run into a type 
of mathematical description which transcends physics in its 
essential mysticism. This new science is very new, only a few 
years old. It may be too beloved by the gods to survive, for 
" those the gods love die young." It may grow up and become 
extremely unlike its baovship. But in any case it stands 
already triumphant as a tneory which stands all square with 
experimental facts. 

After a great outburst of mathematical physics there has 
been a noteworthy return to high achievement in the 
laboratory, particularly in connection with cosmic radiation, 


with the positron, the neutron, and such striking confirmation 
of the correctness of the general viewpoint on atomic struc- 
ture as the production of two alpha particles from lithium 
(atomic mass 7) and a swift proton entering its nucleus. 
Further developments in this direction are eagerly expected, 
and in the meantime it is interesting to note that two great 
authorities, Einstein and de Sitter, 1 assure us that there is, at 
present, no certainty as to whether the radius of our three- 
dimensional universe is positive, zero or negative that is, 
whether the general character of the large-scale geometry of 
the universe is elliptic, Euclidean or hyperbolic in type, so 
that the size of the universe may or may not be finite, 
although this problem may be capable of solution when there 
are more astronomical data available. 

On the other hand, it seems to be well established that the 
distant nebulas are receding from us and from one another at 
an amazing speed which increases in proportion with the dis- 
tance, the velocity being, in fact, about 500 kilometres per 
second for every million parsecs, where a parsec is about two 
and a quarter light-years. This expansion, of the distances 
between nebulae, is so rapid as to lower the time-scale of the 
universe as derived from other considerations; so that an 
oscillatory universe may be the correct surmise. In any case, 
the old view of a static universe with its " fixed stars " has 
given place to a more fascinating picture of a universe full of 
motion and dynamic complexity. 

1 Proc. Nat. Acad. Sci. of U.S.A., 18, 3, pp. 213, 214 (March, 1932). 


By the late JOHN JOLY, D.Sc., F.R.S. 

Sometime Professor of Geology and Mineralogy, Trinity College, 
University of Dublin 


WE inhabit a world which has had a marvellous sur- 
face history. Physical changes of great magnitude 
have again and again affected its surface structure; 
and on each occasion the changes have been much alike in 
character. The continents over great areas sink down into 
the ocean and the waters close over them. Air-breathing life 
animal and vegetable which for ages flourished over 
these areas has to perish. But the traditions of life are carried 
forwards by the life of the highlands. 

In due course there is a great resurrection and the sub- 
merged land revisits the glimpses of the sun. Life migrating 
from the highlands once more spreads over the lowlands. So 
the history proceeds Life prevailing through it all and 
never altogether forgetful of the past. For there is such a 
thing as organic memory; notwithstanding the fact that 
'onwards and upwards' has been the attitude of the organism 

The complexity of the Earth's surface history has only 
recently been deciphered. To this subject we have patiently 
to confine our attention in the first instance. The reader will 
note the steadily repetitional character of that history from 
age to age; and the actually sub-atomic nature of the forces 
which have supplied ultimately the creative energy; and 
built up the glorious mountains of the earth. He will gather 
that the same stately march of events must continue into a 
future inconceivably remote. 



Again, the reader will note that the advance of life from 
its rudimentary forms to that of Man has proceeded along 
very different lines from those which directed the purely 
physical earth-history. Not that any occult forces have been 
involved, but that events are so regulated in the growth of 
the organism as enables it to evade the immediate conse- 
quences of a certain law of thermodynamics. Hence the 
final triumph of the organism and the existing abundance of 
life upon the Globe; and hence, too, we reasonably infer its 
existence in other worlds than ours. 

The greatest accomplishment of Geological Science in re- 
cent times is the recognition of the fact that the surface 
history of the Earth is marked throughout by repeated in- 
vasions of the sea upon the land. 

The reality of this record admits of no doubt. It is 
detected in the existence of ancient rocks of marine origin 
laid down far within the continental margins of today. Even 
in remote Archaean times vast depths of marine sediments 
were deposited far within the existing continental areas. 

The great invasions of the continents by the waters of the 
oceans constitute, indeed, the leading events of the surface 
history of the Earth throughout all geological time. When 
signalised by the fossil remains of contemporary marine 
organisms they enable us to decipher a definite surface his- 
tory as extending over some hundreds of millions of years. 
Thus we learn that geological history is by no means a 
monotonous ageing of the great continents. Far from it. An 
extraordinary sequence of events was repeated again and 
again. Events revealing no signs of decadence in the great 
forces to which they might be ascribed. 

Some of the greater of these events are best referred to by 
the descriptive name which has been given to them by 
American Geologists : They were so revolutionary in charac- 
ter as to justify the nomenclature which terms them Revo- 


Our knowledge of these Revolutions has been as much 
due to American Geologists as to European. Indeed, as re- 
gards the pioneer work, much of it stands to the credit of 
investigations carried out in the New World. 

Little by little, as field work extended knowledge, it was 
forced upon the early geologists that the mountains them- 
selves were mainly built out of marine sediments. Folded 
and piled-up beds of calcareous strata or arenaceous sedi- 
ments were found to enter into the structure of the Western 
Mountains of North and South America; of the Alps of 
Central Europe; of the giants of the Himalayas, etc. That 
these beds were originally laid down in seas, now long 
vanished, was shown by their fossil content. 

The Geologist was, in fact, presented with a record of un- 
impeachable veracity showing that in many cases where the 
mountains now are there formerly had prevailed wide inland 
seas or mediterraneans. Not very deep, perhaps, at any time; 
but communicating with the great permanent oceans of the 
Earth. Further, it was evident that in those epeiric seas 
there had progressed a steady accumulation of sediments 
shed from neighbouring highlands or secreted by organic 
life; the Earth's crust sinking locally under the ever-increas- 
ing load. 

The sediments so derived were destined to form the future 
mountain ranges. For this to come about compressive 
stresses, arising after the long period of deposition, must 
have folded and uplifted the age-long accumulations of the 
ancient seas. 

In order to arrive at some idea as to the areas of such 
former continental seas the folds of the existing mountains 
must be spread out. When this is done it is found that the 
continents as we know them today must have been for a 
considerable part covered by the epeiric seas. 

The Historical Geologist divides geological time both ac- 
cording to superposition of strata and to organic evolution, 
as the accompanying table shows. 1 

1 The Surface History of the Earth, by the present writer. Second 
edition. Oxford; at the Clarendon Press, 1930. 





(Kaino- < 

Secondary ^ 

(Palaeo- ( 
















Dominance of Man. 

Palaeolithic Man. 

Advent of Man ? Highest orders of mammals 
and plants. 

Continued advance towards recent forms Alpine, 
especially in molluscan and insect life. 

Continued advance towards recent forms. 

Dawn of recent forms of life. A marked ad- 
vance over Cretaceous forms of life, especi- 
ally in the Mammalia, is found in earliest 
Eocene. Early angiosperms. 

' Age of Reptiles ' (both herbivorous and carni- Laramide. 
vorous) on land and in the sea ; prophetic, in 
their various forms, of birds and mammals. 

Remarkable evolution of gastropods, cephalo- 
poda (ammonites), and bivalves, advent of 
Mammalia. Early cycads and conifers. 

Disappearance of Palaeozoic seed ferns, Cor- 
daitales, and Lepidodendraceae. 

Evolution of air-breathing, \ertebrate life con- Appala- 
linued. Advance in insect and plant life. chian. 
Tnlobites disappear. 

Great development of fern-like plants and of 
insect life. 

Ancestral amphibians on the land. 

Bivalve, crinoid, and coral marine life abund- 

* Age of Fishes ' (armoured and enamel- 
scaled types) ; first land floras ; precursors 
of the amphibians ; marine invertebrate life 
abundant, especially molluscs ; brachio- 
pods ; corals. Decline of trilobites. 

Fishes rare at first ; later abundant. Life Cale- 
mainly represented by corals, brachiopods, donian 
trilobites, crinoids, bryozoans and grapto- 
htes : the last become extinct in Silurian 

Advent of true corals and armoured fishes. 
Rise of shelled marine life (lamellibranchs 
and brachiopods) ; bryozoans and grapto- 

Dominance of trilobites ; rise of cephalopods ; 
primitive corals and sponges ; brachiopods 
abundant ; early lamellibranchs and crusta- 
ceans ; land plants and land animals un- 
known. First known marine faunas. 

r Kewee- 
I nawan 
-I Huronian 
I Timiska- 
V mian 
Archaean Loganian 


\ Worms ; radiolaria ; siliceous sponges. 
Calcareous algae. 
No trace of life. 




The most important events of all, as regards Earth-history, 
are the Revolutions. These are, by some writers, referred to 
as " Critical Periods " or " Eras/' 

The Revolutions are named generally after some great 
mountain development : as Alpine, Appalachian, etc. Geolo- 
gists do not always select the same name, being, perhaps, in 
some cases impressed by the orogeny of one area more than 
of another area. 

There is general consensus of judgment as to the periods 
of these great events of Earth-history. Perhaps the only ex- 
ception is to be found in the case of the Laramide Revolu- 
tion which is evident in America but not conspicuous in 

Consider the existing fold-mountains of the Earth's sur- 
face. They are mainly alike in age all over the Globe and 
that age is a geologically recent one. The structural features 
of the Earth presented to us today are just such as would 
arise out of a great Revolution. What can have given rise to 
such structural features? A general shrinkage of the deeply- 
lying sub-continental and sub-oceanic materials of the Globe 
would account for them. Such a shrinkage as would result in 
the folding and crushing of those superficial materials which 
no longer have room to remain outspread upon its surface. 

In the past there were similar world-wide epochs of shrink- 
age and mountain-building. The remains of the worn-out 
mountains are there still and tell us of former Revolutions. 

Now if we seek to account for the repeated periods of 
mountain-building as arising upon the surface of a steadily 
cooling Globe, we have to assume that the surface materials 
possess such perfect rigidity as to resist the accumulated 
stresses of scores of millions of years of cooling and contrac- 
tion before 'simultaneously' yielding to them all over the 
surface of the Globe. 

This assumption is not in harmony with the physical 
properties of the surface materials of the Earth. All manner 
of rocks sedimentary and igneous yield steadily to long- 
continued stresses. The folding of the rocks visible in moun- 


tain ranges is evidence of this fact. There is nothing in our 
observationally-acquired knowledge of mountain structure to 
support such views. 

Plainly we must question the validity of the basal 
hypothesis that the Earth has all along been steadily losing 

The difficulty attending the assumption of a steadily cool- 
ing globe increases when it is recognised that the former 
prevalence of periods of great tensile stresses is abundantly 
evident in the surface rocks. 

The effects of tensile stresses are for obvious reasons gener- 
ally less conspicuous than those arising out of compressional 
stresses. But those who deal with mining operations, etc., 
are familiar with the effects of tensile forces as abundantly 
evident in the Earth's surface structure. 

The most impressive testimony of the reality of epochs of 
tensile stress is to be found in the structural features of the 
African Continent. It is well recognised now that the chain 
of narrow seas extending north and south throughout the 
length of this great continent are the result of tensile forces 
rending the continental rocks to great depths. 

Meridional rifting on a great scale is also conspicuous in 
South-Eastern Australia. 1 

Every fact we know today respecting this matter is op- 
posed to the theory of a steadily cooling earth. It may be 
affirmed that the events of geological history from the re- 
motest past are in discord with the history of a slowly cool- 
ing Earth. But they are in accord with a very different 
history. We have, in short, to recognise that there were 
periodic changes in the volume of the sub-surface materials 
of the Globe, such as would occasion alternate state of com- 
pression and tension of the surface materials the compres- 
sive stresses resulting in the more monumental erection of 
the great mountain ranges. 

Now such a succession of changes can be ascribed to one 
source only : the alternate fusion and regelation of the deep- 

1 Reed, Geology of the British Empire, p. 351, 


lying sub-surface materials of the Globe. In such alternation 
the great phenomena of the Revolutions at once find expla- 
nation. This leads us to consider the evidence available re- 
specting the nature of the Earth's sub-surface materials. 

As leading up to this subject we have first to consider a 
structural surface feature of the Globe of comparatively 
recent discovery. This structural feature known as ' Isos- 
tasy ' was first revealed some 75 years ago by a discovery 
made during certain survey operations carried out in 
Northern India. 

In the course of these operations it was found that a 
plumb-line was deflected towards the Himalayan Ranges to 
a degree sufficient to introduce notable error into the ver- 
ticality of the plumb-line. 

Upon investigation (by Archdeacon Pratt) the curious con- 
clusion was reached that the observed deflection was less 
than that to be expected from the calculated gravitational 
attraction of the great mountains. 

Following upon this discovery Sir George Airy then 
Astronomer Royal suggested an explanation of the de- 
ficient attraction of the mountains: an explanation which 
has revolutionised our knowledge of the surface structure of 
the Earth. It amounts to the, at first sight, daring theory 
that the continents of the Earth are floating in a dense sub- 
stratum which extends universally beneath the continents 
and oceans. 

In short, the continents themselves and the mountains 
thereon float (like great icebergs in the ocean) in sub-con- 
tinental materials sufficiently dense to carry them. We must 
picture the Himalayas, rising into the heavens, as supported 
from beneath by a great projection into the underlying 
denser materials. The ' error ' in the deflection of the plumb- 
line is due to the fact that the attraction of the visible moun- 
tain ranges is off-set in part by the lesser attraction due to 
displacement of the heavier sub-stratum beneath by the 
lighter mountain-building materials. 

This discovery has introduced entirely new views as to the 
surface structure of the Earth. The light continental crust 


floats in a great substratum of heavier materials. The thick- 
ness of the continental layer is much greater than what we 
estimate either from height above sea-level or above the 
level of the ocean floor. This leads us to consider the nature 
of the materials in which the continents are floating: 
materials which must, of course, be denser than the con- 
tinental materials. 

The average density of the continents, judging from the 
rocks open to our investigation (mainly granites and similar 
highly siliceous rocks), cannot be far from 2-7 times that of 
water. If we assume that the average depth of the ocean 
defines the surface of the substratum i.e., 3-8 kilometres 
and that the substratum in which the continents float is 
basaltic in nature (for which, as we shall presently see, there 
is very strong evidence), then, allowing for the buoyancy of 
the ocean water and taking the mean emergence of the con- 
tinents over sea-level as 0-82 kilometres, we find that the 
total average depth of the continents is about 3 1 kilometres, 
of which 26 kilometres are submerged in the basaltic sub- 
stratum. From other considerations, as we shall presently 
see, the normal thickness of the continents has been com- 
puted to be about 40 kilometres. 

The evidence for the basaltic character of the substratum 
is very strong. 

This rock has played a considerable part in the surface 
history of the Globe. It has been poured out on the surface 
of the continents many times since the commencement of 
geological time. Some of its flows date back to the earliest 
geological periods. Its density is about 3-0. It fuses at about 
1,150 C., at atmospheric pressure, and a little above this 
temperature flows freely. It covers by far the greater part of 
the Earth's surface. There is evidence that the greater part 
if not the whole of the floor of the Pacific is composed of 
basalt. In the case of the Atlantic there is evidence of a 
layer of lighter materials (of continental character) covering 
a basaltic substratum. These facts have been inferred from 
seismic evidence. 

Towards the end of Cretaceous times, or early in Eocene 


times, basaltic outflows along the north-west boundaries of 
Peninsular India covered an area estimated to be not less 
than 500,000 square miles. Over 200,000 square miles to an 
average depth of one half a mile still remain. That is to say 
not less than 100,000 cubic miles were poured out. 

At about the same time similar floods were poured out on 
the sea-floor of North- Western Europe, extending some 
2,000 miles from Northern Ireland to Franz Josef Land and 
to an unknown distance westward over the Atlantic floor. 
This outflow possibly was continuous with plateau basalts 
poured out in Northern Russia. 

In the Western States of North America the Colombia 
River basalts cover some 200,000 square miles. These flows 
reached their maximum in Miocene and Pleiocene times. 
Many other enormous floods occurred in the Front Ranges of 
the Rocky Mountains and along the Pacific coast. The great 
basaltic region of the Parana basin of South America shows 
floods of at least 300,000 square miles in extent. Great out- 
flows are evident in Patagonia and in South-East and North- 
West Australia all of Tertiary age. 

In the earliest times of Earth-history similar floods were 
poured out. 

Now it is characteristic of these Plateau Basalts so-called 
because of the form taken by the flows that all over the 
Earth they are strikingly alike in chemical composition. 

In short, there is very strong physical and geological evi- 
dence that this rock not only floats the continents, but forms 
by far the greater part of the ocean floor and ultimately con- 
stitutes the deeper-lying parts of the floor in its entirety. 
Moreover, it is to be inferred from these great outflows that 
at certain epochs it must become fluid. 

As regards the nature of the deep lying materials of the 
Globe, our knowledge is mainly based upon evidence arising 
out of seismic disturbances such as now and again transmit 
to the seismic observatory vibrations originating in the 

The reality of Isostasy has been accepted by all who have 


studied the subject and has received very conclusive support 
arising out of the work of Hayford and Bowie in the United 
States and in the critical work of Heiskanen and others in 
Europe. Recent observations carried out by Meinesz over 
the great oceans have revealed exceptions in certain limited 
areas only : areas over which stresses in the ocean floor are 
attended by consequent anomalies in isostatic equilibrium. 
The anomalies are described by Meinesz as being " in good 
harmony with the universally prevailing opinion that move- 
ments of the crust took place here in very recent times and 
that they may be even still in progress." 

Again, in the deeps of the ocean defect of gravitation is 
observed. Meinesz considers ' that movements of the crust 
have taken place here in very recent times, and that they 
may even still be in progress/ 

In short, we possess strong evidence that the continents 
great as they are float in a sustaining ocean of congealed 
but viscous basalt; the space between the continents being 
occupied by the still lighter waters of the ocean. This con- 
dition of structural equilibrium has been attained by the 
viscous yielding of the rocks to high temperatures and long 
continued stresses. 

We must now approach the subject of mountain genesis. 
In other words, we have to answer the questions which arise 
out of the present existence of millions of square miles of 
up-raised and folded surface rocks largely of sedimentary 

As already stated, it is impossible to account for the great 
phenomena of the mountains, which plainly reveal the 
former existence of extreme horizontal compressional forces, 
without the assumption that such forces can only have 
originated as the result of a shrinkage of the sub-surface 
materials of the Globe itself. If such a voluminal reduction 
took place in the great basaltic stratum of the Globe such 
folding and wrinkling of the floating sial or granitic rocks 
would find explanation. 

But this is not all for which we have to account. The 
mountains are built as we have seen out of materials 


which plainly were laid down in formerly existing conti- 
nental seas and which must undoubtedly have been in com- 
munication with the general oceans. 

In other words, we have to account for two movements. 
First, a sinking movement of the land i.e., of the conti- 
nents relatively to the surface of the ocean whereby the 
ocean flooded the sunken land areas. And then, secondly, 
after a very long period of time, during which great deposits 
of sediments were accumulated in the shallow continental 
seas, another movement whereby the accumulated sedi- 
ments were folded and elevated into mountain ranges. And 
this consecutive sinking and folding of the continental 
regions of the Earth was several times repeated throughout 
geological history. 

Now these two movements must, obviously, be very dif- 
ferent in character and origin. The first is not apparently 
attended with any marked reduction of the Earth's surface 
area. There is no attendant folding of the continents. The 
movement would appear to have been effectively vertical. 
The second, on the other hand, appears to have been 
attended with very conspicuous shrinking and folding of the 
outer crust. 

This second movement was followed, or attended by, a re- 
elevation of the continents and withdrawal of the epeiric 

Plainly such a succession of events cannot be supposed to 
arise out of the age-long shrinkage of a steadily cooling 

We have now to assign a cause for these remarkable move- 
ments of the terrestrial surface; and, further, we have to 
show why they have been repeated several times in the 
course of the geological history of the Earth. 

There exists in the surface materials of the Globe the 
continental rocks and the sustaining basaltic substratum a 
source of heat practically eternal in its endurance and cease- 
less in its genesis. 

The radioactive elements which give rise to this inexhaust- 
ible supply of thermal energy are present in every rock on 


the surface of the Globe. Very many investigations by 
various methods support this conclusion. The heat-pro- 
ducing elements are more especially abundant in the lighter 
continental rocks of igneous origin the granites and 
syenites, etc. which largely make up the mass of the con- 
tinents. The heavier basaltic materials which float the 
continents and mainly floor the oceans also, but in lesser 
quantities, contain the same sources of thermal energy. 
Finally, the eclogites the heavy basalts which on seismic 
evidence form the deeper layers of the Earth are less radio- 
active still. 

The gradient of temperature everywhere observed in deep 
borings or mines in the continental rocks must be ascribed 
solely to this thermal source. In fact, simple calculation 
shows that it is quite adequate to account completely for 
the temperature gradient. The variability of this gradient 
from place to place being doubtless due to differences in the 
radioactivity and thermal conductivity of the rocks involved. 

At a certain depth the radioactive continental rocks give 
place to the less radioactive and heavier basalts, in which, as 
we have seen, the continents float. Estimates of the probable 
temperature prevailing at the base of the continental rocks 
suggest that at their greatest depths the temperature of these 
rocks must be nearly that of the melting point of the basaltic 
substratum at its very top. These conditions prevailing in 
the depths lead to the conclusion that the radioactive heat 
continually being generated in the sub-continental basalt 
must, at the present time, be accumulating in its entirety 
and must ultimately result in the fusion of the basaltic sub- 

Here we must again revert to the well-proved fact of 
isostasy governing the relations of the continents and the 
substratum. For arising out of this relationship it is obvi- 
ously inevitable that the fusion and loss of density of the 
substratum must involve a sinking of the continents. They 
must sink for the same reason that a ship sinks a little when 
it passes from the ocean waters to the less dense waters of 
the river. 


It is this accumulative effect of age-long radioactive energy 
which brings about the sinking of the continents relative to 
the ocean; thereby causing the inflow of the ocean waters 
upon the land and the creation of the epeiric seas. In short, 
we see that the events responsible for the advent of a 
great Cycle must be ascribed to the radioactivity of the 

Then a very long period some fifty millions of years or 
more succeeds, during which the rivers flowing into the con- 
tinental seas deposit therein such sediments as the denudative 
activity of millions of years may create: such loading 
resulting in continually progressing submergence of the 
continental floor. But ultimately certain events put an 
end to these great preparations for the future mountain 

In order to understand these events we must first refer to 
the physical history of the oceanic areas of the Earth. 

The rocks underlying the oceans and extending down- 
wards for some scores of kilometres are basaltic in character, 
as we have seen. Now these basaltic rocks like the rocks 
forming the continents must rise in temperature down- 
wards, due to their own proper generation and accumulation 
of radioactive heat. At a certain depth the melting point will 
be attained. Beneath that level all the radioactive heat con- 
tinually being generated will go towards supplying the latent 
heat required for ultimate fusion. This will require some 50 
millions of years or more to come about. 

Beneath the continents, as we have seen, similar changes 
are progressing, and from the base of the overlying conti- 
nents downwards fusion is progressing more and more as the 
successive millions of years pass away. 

Two great events arise out of the general liquefaction of 
the deep basaltic substratum. In the first place the expansion 
attending fusion affects the surface area of the entire Earth. 
It is only very roughly calculable because we know but little 
as to the compressibility of the fluid basalt. But it seems 
safe to assume that ultimately it might result in increasing 
the surface area of the Globe by some 1,700,000 square kilo- 


metres (650,000 square miles). This estimate omits effects 
due to volume-change of an eclogitic substratum. The speci- 
fic volume-change affecting such a substratum would be not 
less than some 20 per cent, in excess of that of a normal 

Now this great increase in the volume of the substratum 
must result in general tensile forces affecting the still solid 
floor of the oceans and of the overlying continents. For, in 
fact, the whole surface has to grow larger in order to accom- 
modate the expansion of the sub-surface materials. Rents 
will develop in the ocean floor and basaltic lava will be 
poured out and many volcanic islands will come into exist- 
ence. Such rents are possibly traceable in the remarkable 
parallel-linear distribution of the oceanic islands of the Paci- 
fic, and have probably given rise to the great lava-flows along 
the ocean margins i.e., the Hebridean and Deccan traps, 
etc., as already referred to. Such great tensile effects as have 
rent the African continent would also find explanation in 
these deep-seated volume changes of the Globe. 

But a second important indeed, critical event also 
comes about and one which averts much of the danger of 
cataclysmic results developing and gravely affecting the 
stability of the continents. In order to understand clearly 
the event referred to we must look back to a foundational 
and now well-known mathematical investigation due to Pro- 
fessor Love. The investigation had reference to the question 
as to the possible existence, at the present time, of a fluid 
layer beneath the outer crust of the Earth. Love found that 
such a layer cannot now exist; for, if it did, effects upon the 
oceanic tides must reveal its existence. There might be 
patches of molten matter here and there, but a continuous 
fluid layer there could not be. 

A general understanding of Love's investigation is easy. 
The solar and lunar gravitational attraction, as tending to 
withhold preferentially the outer crust towards the west, 
would, in the case of a fluid layer underlying the continents 
and ocean floor, give rise to movements of the outer crust 
relative to the inner core, so that the deeper layers would 


fain upon it in the general west-toeast rotation of the 
arth. 1 

The importance of this conclusion in the past history of 
the Earth cannot be over-rated. It explains why the radio- 
active conditions which affect the outer materials of the 
Globe have not resulted in the destruction of all life upon its 
surface. It confers upon the oceans yet another function in 
the biological history of the Earth. 

For, as we have already seen, at a certain stage in the pro* 
gress of a great Revolution a deep fluid layer must develop 
beneath the continents and beneath the water-cooled ocean 
floor. The slow relative movement westward of the rigid 
outer crust, consisting of the continents and ocean floor, 
must result in the highly heated sub-continental lavas being 
brought beneath the ocean floor. Through this floor the 
superfluous heat escapes into the ocean throughout the suc- 
ceeding ages, and the continental layer is thereby saved from 
destruction. Many millions of years may be involved in 
these movements. 

There is good evidence in the foundering of marginal con- 
tinental tracts such as those forming the eastern extension 
of Asia and those known to have formed, in remote times, a 
part of Eastern North America for the former existence of 
these conditions. For such cataclysmic faulting and founder- 
ing of great tracts can only be accounted for by the melting 
away of the supporting compensations. 

We notice that the preservation of life upon the land is 
not obtained at the cost of life in the ocean. Its waters con- 
vey away the escaping heat with but little rise in tempera- 
ture. The resolidification of the entire basaltic substratum 
is ultimately brought about in this way. 

Attending the escape of the accumulated heat from sub- 
crustal depths the successive events of a great Revolution are 
being further developed at the surface of the Earth. For the 
thermal loss involves the voluminal shrinkage of the entire 
substratum and concurrent, ever-accumulating, pressure con- 

1 See also a lecture by Sir Arthur Eddington, "On the Border- 
land of Astronomy and Geology," Nature, January 6, 1923. 


ditions in the surface rocks. The applied force may be re- 
garded as derived from the ocean floor, the thickness of 
which as a rigid body may be taken as some 30 kilometres 
at this time. 1 

This solid crust bears everywhere against the continental 
coasts. In some regions very slowly and irresistibly crushing 
the accumulations and flood of the epeiric seas and uplifting 
them into mountain chains. 

The yielding of the continental structure arises naturally 
and inevitably out of the prevailing conditions. For on the 
one hand the continents are at this period more heated than 
the ocean floor. A fact due not only to their much greater 
radioactivity, but also to the absence of a universal over- 
lying ocean of vast depth and thermal capacity such as cools 
the sub-oceanic basalt. Again, the continental rocks do not 
possess the homogeneity of the great basaltic sub-oceanic 
layer. Finally, the compressional strength of basalt among 
rocks is exceptionally great, if not the greatest known, and 
far above that of the secondary rocks entering into the con- 
tinental surface structure. 

It is interesting to consider what is actually involved in 
sub-continental events attending a great Revolution. In the 
first place we recognise that in the substratum there exists a 
continuous and inexhaustible genesis of heat. We know this 
from our knowledge of its basaltic character and our exten- 
sive knowledge of these rocks. In the depths such a sub- 
stratum must ultimately melt. But Love's result shows that 
a general fluid layer exists nowhere at the present time 
among the outer materials of the Earth. Taken together 
these two conditions can only be reconciled in one way: the 
former occurrence of the Revolutions. For in this periodical 
manner only is it possible for the accumulated heat to escape 
through the ocean floor. 

How long might these successive events require for their 
development and consummation? 

Calculations based on direct measurements of the radio- 
1 The Surface History of the Earth, second edition, p. 203. 


active contents and latent heat of many scores of samples 
of the rocks concerned suggest the lapse of some 48 or, say, 
50 millions of years for the upper layers of the substratum. 

Beneath the oceans the basaltic substratum is continued. 
In the case of the Pacific the basalt reaches nearly to the 
waters of the ocean. In the case of the Atlantic it is believed 
to be overlain by a layer of continental materials. 

Preceding the advent of a Revolution we may assume that, 
in the case of the Pacific, the solid sub-oceanic basaltic floor 
is approximately at o C. at its surface, the temperature ris- 
ing slowly downwards until a depth of about 32 kilometres 
(20 miles) is reached, beneath which the escape of heat be- 
comes very slow. This estimate is due to J. R. Cotter (Phil. 
Mag., September, 1924). Heat generated above this depth 
escapes into the ocean. Beneath it the heat accumulates much 
as heat accumulates beneath the continents. As we have 
already seen, some 120 millions of years might be required 
in order to bring about the liquefaction of the deeper parts 
of the substratum. These figures are closely related to such 
estimates as we can arrive at respecting the time-period re- 
quired to bring about a Revolution. For we may consider 
that at the close of a Revolution the basaltic layer is left in 
a condition of solidity; the preceding Revolution resulting 
in the loss of the latent heat of fusion and the regrowth of 
the basaltic ocean floor from its (practically) limiting depth 
of 32 kilometres upwards. Above this depth the radioactive 
heat escapes slowly into the ocean. Beneath this depth it 
accumulates. As stated above, liquefaction would ensue in 
some 1 20 millions of years. 

Estimates of the antiquity of the ancient rocks based on 
the analysis of ores of uranium and thorium have been re- 
peatedly attempted. It is assumed that the rate of radio- 
active changes in these ores will be constant over geological 
times. In both cases the final product is lead : the lead being 
different in atomic weight from ordinary lead and different 
also according as it is derived from uranium or thorium. 
Results exhibiting very often unaccountable disagreement 


have been obtained in this manner. Lately Clarence A. M. 
Fenner records (Am. J. of Science, November, 1928) con- 
cordant results obtained by such measurements. He takes 
special precautions against the presence of decomposition 
products, etc. He obtains the same ' age ' from both ores 
i.e., 360 millions of years. 

On the subject of the time-periods involved in the Major 
and Minor Revolutions we do not seem able at the present 
time to advance any further than we have gone. It must 
suffice to keep in view the strong evidence for both longer 
and lesser time-intervals between crustal disturbances as 
arising out of the surface structure of the Earth. We may 
claim to have arrived at data enabling us to account for 
lesser Revolutions arising out of more superficial thermal 
accumulation and for greater Revolutions wherein the depths 
of an eclogitic layer 60 kilometres deep are involved; and 
possibly, along with this, thermal accumulations nearer the 
surface. That there would be a certain degree of rhythm 
affecting the Revolutions is obviously to be expected. 

We turn to the bearing of the foregoing theory of Earth- 
history on the Geographical features of the Globe. 

(a) The relative areas occupied by land and water can be 
traced to factors which limit continental thickness. Obvi- 
ously, given a certain definite amount of the lighter, more 
acidic, continental materials as segregated out of the uni- 
versal basaltic layer, the area occupied by these materials 
must depend upon the depth of aggregation. 

Now the total continental depth is controlled within certain 
limits by considerations arising out of their radioactivity. 
For the basal temperature, due to intrinsic radioactive 
content, varies as the square of the continental depth. If 
this depth is sufficiently great heat will flow downwards into 
the underlying magma and temperature conditions may be 
attained during the prolonged period of thermal accumula- 
tion which will soften and ultimately melt the deeply sub- 
merged continental materials. In this event the fluid 
material would escape from beneath the continent and dur- 
ing the tidal movement of the outer crust would emerge 


principally on the eastern continental margin. This effect is 
supplemented by denudative degradation at the surface 
which also tends to spread the continent laterally. Acting in 
the opposite direction, during the orogenic period the com- 
pressive forces proceeding from the ocean floor fold up the 
geosynclinal deposits and tend to restore the original con- 
tinental thickness. 

Under the play of these opposing effects the continents as 
we know them have been moulded, and, of course, the water 
collected at the earth's surface must occupy the residual 
area : the mean oceanic depth being defined by the extent of 
that area and by the quantity of the water. 

At the present time there are considerable differences in 
the mean emergence of the several continents. Obedient to 
isostasy, a highly emergent continent corresponds to a 
greater mean submergence. But we live in the period im- 
mediately following a great revolution, and the effects of the 
mountain-raising forces must continue unmodified for long 
ages to come. Doubtless the slow adjustments, arising out of 
excessive thermal accumulations beneath, account for a con- 
siderable part of inter-revolutionary fluctuations of level and 
even local orogenesis, such as have been recorded in many 
parts of the world and at divers periods in its surface history. 

(b) The distribution of land and water upon the surface 
of the globe is not what would have been expected upon a 
planet possessing so great an axial velocity. There are, in- 
deed, forces arising out of this high velocity which urge the 
elevated features of the crust i.e., the continents towards 
the equator. These forces are feeble, but they have been in 
operation all along and may have been greater in the past. 
Nevertheless, the disposition of land and water is far from 
being equatorial. Quite the opposite, we may say, because a 
distinctive geographic feature of the globe is the existence of 
seas extending without interruption from pole to pole. The 
small Antarctic Continent cannot be regarded as qualifying 
this statement. 

The explanation of this geographic feature of our world 
is to be found in the simple fact that any other disposition 



must be unstable and could not persist over geological time. 
A belt-like continent encircling the globe parallel with the 
equator would infallibly break up under the conditions lead- 
ing to a great revolution. For the discharge of sub-conti- 
nental heat into the ocean could not take place. The tidal 
drift of the surface crust which, under the present geo- 
graphic disposition of land and water, brings about this dis- 
charge would be powerless to effect relief if such movement 
left the emergent land still blanketing the underlying sub- 
stratum with an adiatherminous covering. Under the stresses 
arising from the expanding substratum the encircling land 
mass must rupture, doubtless along rifts extending in longi- 
tude, for no ocean floor would intervene to take up the 
stresses acting in latitude. As the radioactive heat went on 
accumulating the basal rocks of the continents must ulti- 
mately soften and liquefy. Thus we can sec no other ending 
than a general break up into insular forms. 

These considerations lead us, in fact, to the view that the 
extension of the continents in longitude and their severance 
by broad oceans must be the most stable disposition under 
the conditions arising out of a radioactive substratum. That 
this disposition is predominant in geography would be better 
appreciated if we could contemplate the earth after the 
depth of the ocean was reduced by a few hundred fathoms. 
Australia w r ould then form the southern termination of a 
great meridional extension of the land towards the south. 

(c) The relatively minute vertical scale upon which the 
raised surface features of the Globe are modelled arises 
necessarily out of the instability which assails compensations 
extending beyond a certain depth into the substratum. Thus 
it can be shown that the Tibetan Plateau approaches the 
limits of stability. So greatly extended a mass must find full 
isostatic compensation. If its internal temperature has now 
reached a steady state there must be a considerable down- 
ward flux of heat into the substratum and an interior tem- 
perature approaching the softening point of quartz. Its 
stability as a whole, however, may be adequate, for this only 
applies to a limited central region; but it is evident that 


much greater surface features would not be stable. The 
mountains are, of course, not individually compensated. 
The stiffness of the crust distributes the load. In this way 
the surface features may attain locally elevations which could 
not be maintained over large areas. Thus, ultimately, we 
find that, except for small surface features, the existence of a 
radioactive substratum and the great fact of isostasy govern 
the vertical relief of the globe. 

(d) In the past, at long intervals and in the periods im- 
mediately succeeding the great revolutions, cold climatical 
conditions have affected the whole surface of the globe and 
left many geographic features behind them. Many geolo- 
gists ascribe this effect as largely due to conditions of general 
high elevation of the land. It is a not improbable explana- 
tion. When the substratum finally consolidates and the 
compensations are pushed upwards it is doubtless true that 
the average continental level is for a period very high. Data 
respecting the elevation of the land in Pleistocene times are 
not always consistent, but the general high level of the 
North American continent at that period seems to be certain. 

The meteorological effects of a general continental eleva- 
tion by a few hundred metres may be considerable and, not 
improbably, self-intensifying. But this matter has been 
already discussed by many writers and need not be dwelt on 

(e] The principal geographic effects arising out of the 
periodic liquefaction and solidification of the substratum are 
to be witnessed in the mountain systems of the earth. 
Whether the entire work of orogenesis be ascribable to the 
alternate enlargement and reduction of the surface crust or 
whether they are in some part referable to forces attending 
the tidal shifting of this outer crust, cannot here be dis- 
cussed. The latter possible source of orogenesis has yet to 
be quantitively evaluated. Meanwhile we are safe in ascrib- 
ing to the changing area of the Earth's surface by far the 
larger part of mountain development over geological time. 

The orogenetic movements need not necessarily take effect 
close to the continental margin, although it is probable that 


there the stresses are greatest and there the primitive eleva- 
tion which initiates the geosyncline is most likely to 
originate. But in the case of the mountain systems of 
Eurasia there is plain evidence of the transmission of stresses 
far into the interior. Some bodily movement of the African 
Continent and of India may even have taken place. A move- 
ment easily understood when it is remembered that the com- 
pression in longitude was developed over the greatest ocean 
stretch of the Globe. The wrinkling of Asia to its centre by 
these great stresses and the opposing ones acting from the 
North need not excite credulity; for, in fact, the horizontal 
stresses must be conveyed through the entire surface crust 
of the earth. We may be sure that wherever the geosyncline 
has been formed and an area of feeble resistance created the 
horizontal compressive stresses will find it out. 


The surface history of the Earth embraces the history of 
life upon the Globe. Without the fossil of the once living 
organism we had known but little of historical geology. In 
the recognition of the ubiquity of the organism in terrestrial 
space and its restriction in time Stratigraphical Geology 
originated. In these concluding pages I shall enter a little 
way into the subject of Life and its attributes as these affect 
our subject. 

The study of the rocks tells us that life dates back to very 
early times. Many geologists refer the first appearance of life 
upon the Globe to Archaean (Archeozoic) times. They con- 
sider that in certain rocks laid down in those remote ages 
there is evidence for the existence of the less complex forms 
of life such as algae and bacteria. Henceforward the history 
of life upon the Globe has been one of continual expansion. 
Abundant life has penetrated even into the greatest depths of 
the oceans; surviving the unchanging icy temperatures of the 
great depths and living and multiplying in sunless regions. 


Considering its marvellous aggressiveness we may well ask : 
In what manner is the organism distinct from the rest of 
Nature the rocks, the waters, the atmosphere, the sun- 
shine? . . . Plainly it differs in its properties from all these. 

Many years ago, when wandering in the Dolomites of 
South-East Tyrol along with one who is now the learned 
Professor of Botany in the University of Dublin, 1 the fore- 
going question was presented to us with special force by the 
nature of our surroundings. 

We had reached the Pass of Tre Croci, and, from a point a 
little below the summit, looked eastward over the glorious 
Val Buona. The pines which clothed the floor and lower 
slopes of the valley extended their multitudes into the 
furthest distance among the many recesses of the great 
mountains and into the confluent Val di Misurina. In the 
hot sunshine the Alpine butterflies flitted from stone to 
stone. The ground at our feet and everywhere throughout 
the forests teemed with the countless millions of the small 
black ants. 

It was a magnificent display of vitality of the aggressive- 
ness of vitality assailing the heights of the limestone and 
wringing a subsistence from dead things. And the question 
presented itself with new force : " Why the abundance of 
life and its unending activity?" 

In endeavouring to answer this question we may, in the 
first place, offer a definition of the living organism as being 
"a material structure which absorbs energy acceleratively 
from its surroundings." 

The meaning of this statement is apparent if we consider 
a simple case : that of vegetable growth. The leaf exposed 
to solar rays enlarges because of the effects of the radiant 
energy which it receives, and, in doing so, it absorbs more of 
the rays. 

It is certain that this simple principle is at the basis of all 
organic life. It applies to the smallest microscopic organism 

1 Professor H. H. Dixon, F.R.S., Proc. Royal Dublin Soc, vol. vii., 


and to the greatest inhabitant of the forests or of the ocean. 
In such an evident dictum we recognise the basis of the 
whole of evolutionary life upon the Globe. Its struggle for 
existence; its power of self-reproduction; its trials in every 
direction for fresh energy supplies; its wonderful ingenuity 
in securing and making use of them. 

We may contrast the attitude of living and dead nature 
somewhat as follows : 

" The transfer of energy into the animate material system 
is attended by effects conducive to the transfer and retarda- 
tive of dissipation." 

Of the inanimate material system we may say: " The trans- 
fer of energy into an inanimate material system is attended 
by effects retardative of the transfer and conducive to dis- 

The student of thermodynamics will recognise in the last 
statement the second law which involves that whenever 
work is derived from heat a certain quantity of heat falls in 
potential without doing work and is dissipated. On the other 
hand, work may be entirely converted into heat. The result 
being the heat-tendency of the universe. Heat being an un- 
directed form of energy seeks, as it were, its own level, so 
that the result of this heat-tendency is continual approach to 
uniformity of potential. 

We must regard the organism as a material structure 
which is so contrived as to evade or delay the tendency of 
the more fundamental law of dead nature: the tendency 
towards loss of potential. It may, indeed, absorb and accu- 
mulate energy without limit when unconstrained. The facts 
and generalities concerning evolution must presuppose an 
organism endowed with the quality of the progressive 
absorption of energy and of its retention. The continuity of 
organic activity in a world where supplies are intermittent 
is only possible upon the latter condition. 

We can trace the periodic succession of individuals on a 
diagram of activity with some advantage. Considering, first, 
the case of the unicellular organism reproducing by subdivi- 
sion and recalling that conditions, definite and inevitable, 


oppose a limit to the rate of growth, or, for our present pur- 
pose, rate of consumption of energy, we proceed as follows : 


Along a horizontal axis units of time are measured; along 
a vertical axis units of energy. Then the life-history of the 
amoeba, for example, appears as a line such as A in Fig. i. 
This line starts at the point of origin of the axes of reference. 
During the earlier stages of its growth the rate of absorption 
of energy is small; so that in the unit interval of time, t, the 
small quantity of energy, e l9 is absorbed. As life advances, 
the rate of activity of the organism augments, till finally this 
rate attains a maximum, when e 2 units of energy are con- 
sumed in the unit of time. At any moment of its life, the 

rate of activity, -r> is represented by the trigonometrical 

tangent of the angle made with the axis of time by a line 
tangential to the curve at the point in question. 

On this diagram a reproductive act, on the part of the 
organism, is represented by a line which repeats the curva- 
ture of the parent organism originating at such a point as P 
in the path of the latter, when the rate of consumption of 


energy has become constant. The organism A has now 
ceased to act as a unit. The products of fission each carry 
on the vital development of the species along the curve B, 
which may be numbered (2), to signify that it represents the 
activity of two individuals, and so on, the numbering 
advancing in geometrical progression. The particular curva- 
ture adopted in the diagram is, of course, perfectly im- 
aginary; but it is not of an indeterminable nature. Its aver- 
age course for any species is a characteristic of fundamental 
physical importance, regarding the part played in nature by 
the particular organism. 

It matters not if the duration of individual life be long or 
brief. Brevity of life is generally associated with rapid repro- 
duction. The principle is the same, even for the most 
ephemeral; those born with the rising of the sun and dying 
with its setting : life, love and death encompassed in a day. 
Thus we see in the abundance of life around us a mar- 
vellous display of ingenuity. Each individual, whether great 
or small, during its life strikes out a * curve of activity ' where 
the ordinates are energy and time. Inability to prolong the 
curve indefinitely is evaded by reproduction so that the 
activity of the new generation becomes the many-branched 
repetition of the worn-out parental curve. The entire succes- 
sion still ever advancing towards increasing animate energy. 
The result of the whole wonderful phenomenon is that 
nature around us thrills with the presence of the animate 
notwithstanding the fact that death remorselessly awaits the 
individual. For although the individual dies death is not the 
end : life being a rhythmic phenomenon. 

Through the passing ages the waves of life persist. Waves 
which change in their form and in the frequency to which 
they are attuned from one geologic period to the next. But 
which still ever persist and still ever increase. And in the 
end the organism outlasts the generations of the hills. 




Assistant Professor of Astrophysics, Imperial College of 
Science, London 

IT is a fact of experience that no account of modern 
astronomy can protect itself from misinterpretation 
unless it insists in the clearest terms that it is mostly 
untrue. This is not criticism but definition : it expresses the 
fact that the greater part of modern activity in astronomy is 
concerned with the construction of an ideal model of the 
universe and its contents out of insufficient knowledge. There 
is nothing in this with which to reproach the astronomer; 
he acts as he does for a perfectly legitimate purpose, and is 
not as a rule unduly prone to attribute permanent reality to 
the temporary creations of his brain. His purpose is com- 
plex, but its chief element is the desire to obtain more know- 
ledge. He can do this most effectively by trying to arrange 
his present store into a self-consistent whole, the difficulties 
which he meets with in this operation being his most sugges- 
tive pointers to new knowledge. 

The chief danger of the popularisation of science at the 
present time is that the tentative character of scientific 
theory may be forgotten. It is not, however, the only danger. 
The fact may be remembered too exclusively. If astronomy 
speculates she speculates on a basis of established knowledge, 
and to question the knowledge because the speculation is 
hazardous is possibly even more foolish than to give free 
rein to credulity. The actual discoveries of modern astronomy 
are only less impressive than the implications of its theory, 
and whatever changes in outlook, whatever improvements 
in the means of observation, and whatever new discoveries 
may be made in the future, they will remain as permanent 



elements of our knowledge. We hail a theory with hope, but 
we accept a fact with conviction. 

If, now, we are led from these considerations to suppose 
that modern astronomy can be sharply divided into fact on 
one hand and theory on the other, we shall greatly err. The 
transition is gradual, and while of some notions it may un- 
equivocally be said, " This is theory and that is fact," there 
is a very large portion of the subject which cannot be com- 
pressed into such a limited classification. This point is of 
the greatest importance. We are no longer so hot for cer- 
tainties as we were, the dusty answers of past generations 
having tempered our ardour in this respect, but we do want 
to know what particular small department of our knowledge 
is certain and what degree of probability we can safely 
attach to the remainder. The question is difficult, and is 
evidently not to be fully answered in a small compass : we 
must attempt an answer, nevertheless, because of its im- 

To begin with, we may accept the evidence of direct 
general observation of the existence of bodies as certain; 
otherwise science has no basis. Without entering into meta- 
physical discussions, we may to direct observation add ob- 
servation at the telescope and by photography. When we 
say that a certain region in Perseus contains at least 20 
nebulae, we are making a statement which time will not dis- 
prove. Determinations of distance stand on lower planes of 
certainty, although in many instances, when their range of 
possible experimental error is given, they may be accepted 
as beyond correction. No astronomical distance can be 
measured as a cricket pitch is measured, by laying standard- 
ised rods or a standardised tape along its length. Less direct 
methods have to be chosen; e.g., the process of triangulation 
used in surveying large areas of terrestrial land. By this 
means we find that the mean distance of the Sun from the 
Earth is 92,870,000 miles, with an error of less than one- 
tenth of i per cent. Mr. Bernard Shaw, on being told of this 
figure, is reported to have expressed astonishment at the 
magnitude of the lie. If it is a lie, however, we must say that 


the statement that Mount Everest is approximately 29,000 
feet high is also a lie, for both figures are obtained by the 
same means and according to the same principles. We may 
take the distance of the Sun as scarcely less certainly deter- 
mined than its existence. 

The distances of the nearer stars are found in the same 
way with, however, a greater possible range of experimental 
error but for the more distant stars other methods must be 
employed. For instance, when we know the distance of a 
star we can calculate its intrinsic brightness, and on so doing 
we find among the nearer stars a definite relation between 
the brightness and the kind of light a star sends out. Ob- 
serving, then, the kind of light sent out by a distant star, we 
infer its brightness and then calculate its distance. Dis- 
tances found in this way are clearly less certainly deter- 
mined than the distance of the Sun. Not only is the margin 
of possible error greater, but the conclusion that what we are 
measuring is actually the distance of the star involves cer- 
tain assumptions which we cannot absolutely prove to be 
justified. When we extend the process to still more distant 
regions of space the hazard becomes greater, and so we find 
some astronomers maintaining that the stellar system is 
many times as extensive as others believe it to be. The 
difference is mainly not a matter of inaccurate measurement, 
but a consequence of the fact that various indirect methods 
are employed and astronomers have varying ideas of their 
relative degrees of validity. We evidently get further and 
further from absolute certainty as we recede in space. 

Still further circumlocution characterises our descriptions 
of the velocities of bodies. Velocity on the Earth is measured 
by the space traversed in a chosen interval of time : velocity 
in the sky is chiefly measured by the positions of lines in the 
spectra of the bodies concerned. To establish the identity of 
the concepts which are said to be measured by these widely 
different processes we should have to prepare a statement 
of considerable length including a little experimental evi- 
dence and some assumptions. The statement may be con- 
vincing it usually is, in fact but in the last resort it rests 


on circumstantial evidence, not on rigid proof, and certain 
of the more recently measured velocities lead to such re- 
markable conclusions that some astronomers are seriously 
questioning whether what has been measured is really 
" velocity " in the ordinary sense or something quite different. 

When we come to the problem of the physical conditions 
existing in the heavenly bodies we are in the realm where 
theory predominates considerably over fact. The surface 
temperatures of stars, for instance, range from highly prob- 
able values, such as that of the Sun, to others which we are 
forced to qualify by such terms as " colour temperatures " or 
"ionisation temperatures" to distinguish the sometimes 
widely differing results obtained for the same star when the 
necessary assumptions which must be made are different. 
In the interiors of stars, matters are far more speculative, for 
of these regions there is no observation at all to guide us. 
Consequently we find a modicum of agreement almost com- 
pletely overwhelmed by a confusion of conflicting ideas. No 
one can say how much of our present picture of stellar con- 
stitution will survive in ten years' time, but very few will 
expect more than a small portion. 

Finally, when we come to the universe we are in a realm 
of pure theory. Not only have we never beheld the universe, 
but our speculations themselves involve the impossibility of 
our ever doing so. There is not a single statement which we 
can make about the universe as a whole with even the cer- 
tainty belonging to our knowledge of the velocities of the 
stars. The universe of astronomy is a creation of the astrono- 
mer's mind. 

It is important that these ideas should be expressed, but it 
is equally important that they should not be misapprehended. 
They are applicable not only to astronomy but to all science 
and to ordinary daily life. A discussion of astronomy calls 
for their emphasis only because the proportion of certain 
knowledge is smaller there than in most sciences and be- 
cause for some reason men are prone to base their theologies 
and philosophies more on the great and the unknown 
than on the ordinary familiar commonplaces of experience. 


TQ such as are ready to dogmatise about the character and 
attributes o Deity from the " revelations " of astronomy, it 
is necessary to point out the nature of the ground on which 
they stand, but if there are any who thereupon turn from 
astronomy as from a tissue of arbitrary guesswork, they must 
be reminded that the scrutiny to which we have here sub- 
jected astronomy would leave scarcely one of their ordinary 
instinctively adopted notions unchallenged. If our know- 
ledge of stellar distances is indirect, so is our knowledge that 
Napoleon was defeated at Waterloo. The velocities of the 
stars are established with no more uncertainty than the 
commission of any unwitnessed crime; and we are entitled 
to speak with greater confidence about the internal condition 
of a star than about the internal condition of Russia. The 
real significance of the last few paragraphs will be dealt with 
at the end of this chapter. In the meantime let us hear what 
modern astronomy has to say, and suspend our judgment of 
its value. 

The solar system, of which our Earth forms a part, was 
once the centre of astronomical interest. It is now compara- 
tively neglected. This is not because it has no secrets yet 
unread or because our devices for reading them are ex- 
hausted; it is because we have changed our point of view in 
order to scan the universe from the most advantageous 
angle, and from the new viewpoint the solar system is 
scarcely perceptible. Stress must be laid, however, on the 
comparative nature of this neglect. Judged by the standard 
of a hundred years ago, our present discoveries in the solar 
system are sensational : it is only against the background of 
stellar astronomy that they are inconspicuous. During 1931 
the discovery of 13 comets made scarcely a ripple on the sea 
of astronomical knowledge; 200 new minor planets were 
found in the system, but no astronomer's heart was thereby 
made to beat faster. A few years ago the discovery of a new 
major planet, now known as Pluto, created a mild interest 
which has already died down, whereas the echo of a similar 
discovery in 1846 reverberated to the end of the nineteenth 


century. The Sun, it is true, attracts considerable attention, 
but not as the ruler of our system. It is studied because it is 
the unit of the galactic host which happens to be nearest to 
us. Modern astronomy, like Swinburne's God, " gives a star 
and takes a Sun away/' 

One question, however, of universal interest has not been 
outgrown the question of the origin of the solar system. 
Laplace's nebular hypothesis, which in the main satisfied 
the nineteenth century, is unequal to the demands of the 
twentieth. The present idea that the planets were born 
from a primitive Sun by the very close approach or actual 
impact of another star some few thousand million years ago 
owes its acceptance largely to the absence of an eligible 
rival. There is an instinctive feeling against it because of 
what is technically called the " improbability " that such an 
event would happen. The stars are so distant from one 
another that, according to a current estimate, a sufficiently 
close encounter would be experienced by at most one in 
every 100,000 of them. It is felt that there is something of 
the nature of special pleading in claiming this apparently for- 
lorn hope as the source of our existence. 

The feeling is illusory. The mathematical laws of prob- 
ability have no meaning in relation to a single arbitrary 
case. It was exceedingly improbable that a particular Mr. X 
would win a large prize in the Irish sweepstake, but it was 
certain that an arbitrary Mr. Y would win one; and even if, 
as in the present problem, certainty is out of the question, it 
is exceedingly probable, as Aristotle long ago remarked, that 
the improbable will sometimes happen. If it be objected 
that it is highly improbable that such an odd chance should 
happen to us of all beings, the answer is that it did not 
happen to us. It happened, if the hypothesis is true, to 
a quite ordinary, undistinguished star. The fact that we 
developed on a planet of such a star rather than elsewhere is 
then (granting that we were to exist at all) not a matter of 
luck but of inevitability, for life as we know it could not 
have developed anywhere else. If that star had not suffered 
disruption we should not have developed around it but 


around one which had. Whether chance or design be re- 
sponsible for our existence, the present theory of the genesis 
of the solar system is a priori equally justifiable; it is to be 
judged solely on its ability to fit the facts of observation. 
And, conversely, it throws no light at all on the problem of 
whether we exist by chance or by design. 

The solar system, as we now know it, occupies a roughly 
circular area, some 7,500 million miles in diameter. Com- 
pared with the distance of the nearest star namely i^ par- 
sees 1 this is to be regarded as a point. Nevertheless, the 
Sun is not abnormally isolated in space. Except for the com- 
ponents of double and multiple stars systems comparable 
with the solar system so far as their demands on space are 
concerned the stars which form our galaxy are separated 
on the average by distances of a parsec or more. The diameter 
of a single star may be anything from a few tens of thousands 
to a few hundreds of millions of miles in any case a point 
compared with its surrounding region of interstellar space. 
It is truer to say that space is empty of stars than to say that 
the purest water is free from deadly germs. 

In such a vacuum it seems somewhat ridiculous to speak 
of the stars as u thinning out/' but since all distances are 
relative, the phrase has a perfectly definite meaning. If we 
could travel without limit in a straight line from the Sun 
towards the Great Bear, for example, and could measure 
en route the average distance between the stars, we would 
find that after a while this distance would steadily increase 
until we reached a region where, over a range of hundreds 
of thousands of parsecs, space was absolutely empty. The 
same thing would be true of other directions of travel, but 
the distance to which we would have to pierce before reach- 
ing this absolute void would be different in different direc- 
tions. This means that if we could transport ourselves to a 
viewpoint, say a million parsecs away, and look back towards 
the region we had left, we should see an isolated company of 
stars with rather vaguely defined boundaries. This is our 
galaxy, our galactic system, our stellar system, our universe 
1 i parsec = 3 J light-years =19 million million miles. 


it is called indifferently by each of these titles. We will 
shun the last-named, however, reserving it for the totality of 
physical existence, for although the galaxy is vast beyond 
imagination, it is a mere speck in cosmic space one of 
millions of specks of comparable dimensions. To call each 
of these a " universe/' as is sometimes done, is to imply that 
they are unrelated to one another, which is untrue. 

In our galactic system the Sun occupies a highly eccentric 
position. It is, however, well inside the boundaries, so that 
we have the thankless task of surveying what is probably an 
organised system from an internal point. The survey, both 
of dimensions and of form, is consequently far from com- 
plete. We may obtain some guidance, however, from a study 
of other galaxies of which we can command a bird's-eye 
view. We find them presenting various forms, but the form 
which, from both internal and external evidence, seems most 
likely to be the form of our galaxy is that of the so-called 
"spiral nebulas," of which an example is shown in Fig. I. 
The best available photographs of a few of the apparently 
largest (and therefore probably nearest) of these objects show 
that the nebulous-looking arms are crowds of discrete stars, 
perhaps as sparsely distributed as those of our own neigh- 
bourhood, but at the great distances of the nebulae appear- 
ing as dense swarms. The nearest of the spiral nebulae is 
nearly a million light-years away. We may provisionally 
assume that we inhabit one of the arms of a spiral nebula. 

Investigations of the distribution of stars within our galaxy 
support this hypothesis. The plane of the spiral is that of 
the Milky Way, which is, in fact, the appearance presented 
to our eyes by the great depth of star-strewn space through 
which we inevitably look when we turn our eyes towards the 
periphery of the system. Fig. II gives some idea of the 
.apparent density with which the stars are scattered in the 
Milky Way, but it must be understood that the appearance 
of crowding is due almost entirely to the depth of space 
through which we are looking. The actual distances between 
the stars are not appreciably greater than those which separate 
the Sun from its neighbours. The difficulties of the task of 

Photo : Rickey. 

r ig. I. Spiral Nebula. M.33 Trianguli. 

Fig. II.- Great Star Cloud in Sagittarius. 

To face page 272, 

J'/ioto : tfarnard. 

Fig. III. Region of p Ophiuchi. 

To face page 273. 


determining the structure and organisation of our system 
from such photographs as this can readily be imagined, and 
the statement that present results must be accepted only 
tentatively will not be found hard to accept. 

The difficulties are greatly increased by the sporadic occur- 
rence in our galaxy of dark diffuse nebulae 1 patches of ob- 
scuring matter, of which examples may be seen in Fig. III. 
The uncertain amount and situation of this material (whose 
composition is unknown, though there are some not univer- 
sally admitted grounds for believing it to be a mixture of 
dust and gas) gives some uncertainty to all measures of the 
extent of the system. For example, in the direction which 
various phenomena indicate as that of the centre of the 
galaxy, the stars should extend to the greatest distance from 
us, but this appears as by no means the brightest portion of 
the sky. In spite of these difficulties, however, some idea of 
the dimensions of the system has been formed. The greatest 
diameter appears to be between 20,000 and 100,000 parsecs 
the estimates vary considerably within this range while 
the thickness is much less perhaps i/2oth or i/3oth of this 
figure. The two nearest of the spiral nebulae, if our estimates 
of their distances are correct, are about 14,000 and 5,000 
parsecs, respectively, in extent. These figures, though con- 
siderably smaller, are evidently comparable with the dimen- 
sions found for our own system. 

The coiling arms of the spiral nebulae inevitably suggest 
rotation, but their great distances make it impossible, unless 
the velocities are incredibly great, that we should obtain 
direct knowledge of this in the short time during which 
they have been studied. 2 In our galaxy, however, we have 
definite evidence of rotation. The stars travel round the 
centre of the system, not as a rigid wheel in which all parts 
go round in the same time, but in the manner of the planetary 

1 The common name, nebulae, for the spiral and diffuse nebulae, 
must not be allowed to cause confusion between objects which are 
essentially different in character. 

2 There is, however, spectroscopic evidence of rotation of certain 
nebulae which we see edgewise. 



motions round the Sun, the stars farthest from the centre 
taking the longest time to complete a revolution. This differ- 
ence in period, in fact, affords the most obvious evidence of 
the revolution. It is calculated that the Sun, which, accord- 
ing to the larger estimates, is of the order 25,000 parsecs 
from the centre, takes 250 million years to complete its 
circuit: this implies that it has travelled round five or six 
times since the Earth became a solid body. 

The galactic system contains, according to current esti- 
mates, some 100,000 million stars. Certain specific lines of 
inquiry suggest that it has been in existence, in at any rate 
something approximating to its present condition, for many 
million million years, but more general considerations point 
to an age of the order ten thousand million years. Which 
figure is to be preferred is a matter of opinion. It is much to 
be hoped, however, that the data will soon become less equi- 
vocal, for the question has a very close bearing on the im- 
portant problem of the evolution of the stars. Since the stars 
send us light, which is a form of energy, we must believe 
that they are undergoing certain internal changes which, 
however slow they may be, must ultimately have profound 
effects on their constitution. 

The problem of the life history of a star is one which the 
progress of the last few years has seemingly tended to obscure 
rather than to clarify. The nicely rounded-off theory of a 
decade ago is now sadly dishevelled. This, however, gives no 
cause for dismay; it is a familiar experience in the advance 
of knowledge. "When the half-gods go, the gods arrive," 
but the half -gods must go first. The older theory was formed 
mainly as a means of correlating the directly observed char- 
acteristics of the stars their brightnesses, spectral types, and 
so on. It did this excellently, except for one or two puzzling 
faint stars which, then regarded as freaks, are now recog- 
nised to be probably as numerous as stars of any other kind. 
The existence of these bodies (the " white dwarfs," as they 
are called) would be sufficient in itself to cast grave suspicion 
on the theory, but historically what led to its overthrow was 
not so much new facts as a new kind of demand on the 


character of a theory of stellar evolution. Such a theory was 
required to explain not merely direct observations, but the 
hypothetical conditions inside the stars, which were deduced 
according to the laws of physics from what was observed. 
The course of stellar evolution which is sought now is one 
which will be expressed in terms of changes of energy and 
the behaviour of electrons, neutrons, protons and " photons/' 
as unit quantities of radiation are called. When it is found it 
will trace out directly the internal development of a star from 
birth to death. The concomitant changes of observable char- 
acteristics will be rigidly deducible from it, but will not, as 
formerly, provide the language in which it is expressed. 

The sine qua non for such a theory is therefore a definite 
and accurate idea of the state of the stars now, and this we 
do not possess. The problem of stellar constitution was, in 
fact, until lately the centre of perhaps the most vigorously 
conducted discussion in modern astronomy, and the present 
comparative quiescence is merely a pause for the acquisition 
of fresh observational data. The situation is of extreme 
interest, no less psychologically than objectively. The prob- 
lem, in the most general terms in which it is considered, can 
be stated very simply. Given certain observations of the stars 
and certain general laws of physics, it is required to deter- 
mine to what conditions ordinary material must be subjected 
in stellar interiors in order that, when behaving according to 
those laws, it shall give rise to what is observed. This prob- 
lem will repay a little attention, for its consideration throws 
light on both astronomy and the habits of astronomers. 

In the first place, it will be noticed that the problem has not 
been stated in the most general form in which it can be con- 
ceived. There is no a priori necessity to assume that the stars 
shall consist of ordinary material or that their constituents 
shall obey the laws of terrestrial physics. All astronomers, how- 
ever, make both these assumptions, and in doing so they are 
simply conforming to the general canons of scientific method 
enunciated by Galileo in opposition to the Aristotelian doc- 
trine of a fundamental division in Nature between the incor- 
ruptible Heavens and the corruptible Earth. There is no 


rash presumption involved in this conformity. If the sub- 
stance and behaviour of the stars differ from those of earthly 
bodies, then the efforts of theoretical astronomers will be 
fruitless and the difference will thus be made manifest in the 
only possible way. If, on the other hand, the observations 
are successfully accounted for, then that fact will constitute a 
justification of the assumptions made. Those assumptions 
are thus not unquestionable dogma but simply instruments 
of research. To a considerable extent they have already 
justified themselves. For example, the atmospheres of stars 
give spectra identical with those of terrestrial elements, and 
the movements of double stars conform to the law of gravita- 
tion. There is therefore empirical as well as rational ground 
for maintaining the assumptions, and there is complete 
unanimity among astronomers in so doing. It must be said, 
however, that by "ordinary material" is not meant the 
ordinary atoms which compose our matter, but the electrical 
particles which form them. We do not postulate for the 
stars anything but the ultimate constituents of the Earth. If, 
by further research, the electron and proton are broken up 
into sub-electrons and sub-protons, these will become the 
elementary particles of stellar theory and the possibility of 
their amalgamation into systems different from those of the 
electron, neutron and proton will be taken into account. But 
until such a discovery is made its possibility is not considered. 
Admitting this common starting-point, however, the re- 
maining problem still offers ample scope for difference of 
treatment. We begin with certain data and aim at the under- 
lying conditions responsible for them. Two conceivable 
courses at once suggest themselves : we can attempt to 
deduce the conditions directly from the data or, alternatively, 
postulate conditions and see if they issue in the data. The 
former method is the safer, so far as it goes, but it is more 
difficult and does not carry us so far. The laws of physics are 
usually stated in the direction from elementary to complex 
conceptions, and they are not always reversible. Thus, if we 
are told that a substance is hard and has a grey, metallic 
lustre, we can deduce only that it is one of several metals or 


alloys; but if we find that its atoms have atomic number 26 
and have a certain average speed, we know that it is iron, 
and can deduce its hardness, lustre and other observable 
characteristics with certainty. Here, then, is the first way in 
which disagreement can and does arise. 

Next, whichever line of attack is adopted, there is the 
difficulty that the data are not sufficient in themselves to 
determine the conditions uniquely. If we work from data to 
conditions, we reach a point where lack of knowledge makes 
one or more assumptions necessary, and these will be chosen 
according to the taste of the investigator. If we work from 
conditions to data, the assumptions must be made at the 
outset, and their number and character will again depend on 
the taste of the investigator. It must be remembered in this 
connection that the stars are not all alike. They differ in 
brightness, spectrum, mass, density indeed, in every ob- 
servable quality, so that the conditions arrived at must be of 
a sufficiently elastic character to account for all types of stars 
observed, and, to be convincing, must be such as to show 
why stars of other types are not observed. 

Again, the passage from conditions to data, or vice versa, 
is navigable only by means of abstruse and arduous mathe- 
matics. In theory this, being a matter of pure logic, might 
present difficulty but should leave no ultimate disagree- 
ment. In fact, however, disagreement remains. It is to be 
hoped that time will remove it, but the probability is that, 
before that happens, fresh discoveries or developments of 
theory will give the problem a new aspect. 

All this excellently illustrates the character of modern 
astronomical theory, showing on one hand how enormously 
it has extended its scope since the days when it was a matter 
of a single postulate, such as the existence of an undiscovered 
planet, which could be tested by an ad hoc observation; and, 
on the other hand, how intricately it is entangled with the 
psychology of the astronomer. Those who have been accus- 
tomed to rely on the objective, impersonal character of 
science may deplore this, but a distinction must be carefully 
noted. Established scientific results are as impersonal as 


ever; it is only the methods into which temperament enters, 
as, in fact, it has always done, though never so obviously as 
now. Scientific theory is indeed a work of art, supplementing 
the truth of discovered fact by the beauty of conscious 

Although ideas of the internal structure of a star are so 
unsettled, there is a considerable basis of common agreement 
which we may briefly summarise. The surface temperatures 
of at least the great majority of stars range from 2,000 to 
20,000 or 30,000 degrees on the centigrade scale. The atmo- 
spheric material consists of our familiar atoms, sometimes 
" ionised " by the loss of one or more electrons, but never 
more severely handled than atoms which we torture daily 
in our vacuum tubes. 1 The density in the atmosphere is 
extremely low. As we go beneath the surface, both tempera- 
ture and density rise, and the atoms become more and more 
ionised until, in the neighbourhood of the centre of the star, 
there is almost, if not quite, complete independence of the 
nuclei and the surrounding electrons. There is, however, a 
tendency for atoms to form out of these constituent par- 
ticles, so that nuclei will be constantly " capturing " elec- 
trons. The energy of free motion of a captured electron thus 
disappears, and simultaneously a " photon " is created that 
is, a quantity of radiation which cannot easily be pictured 
but which for the present purpose we can best regard as a 
small particle, moving always with the speed of light, whose 
mass depends on the amount of kinetic energy yielded up 
by the captured electron. When the photon encounters 
another nucleus with a captured electron, it liberates the 
electron, and in so doing passes out of existence. The 
photons thus act as intermediaries for exchanging energy of 
motion between the various electrons. 

1 An atom consists of a nucleus, which is a compact but unknown 
association of protons, electrons and neutrons, having on the whole 
a positive charge, round which revolve, at a comparatively great 
distance, sufficient satellite electrons to make the whole atom elec- 
trically neutral. An atom is ionised when one or more of the 
satellite electrons is removed, and the degree of ionisation increases 
with increase of temperature. 


In the star's interior, this process, with all its implications, 
summarises the whole duty of the photons. Starting from 
the centre, where the temperature is higher and their 
number at any moment is greater than at any other place, 
we find that their effect is to transfer energy radially out- 
wards, so that the centre is a kind of source of heat for the 
rest of the star. The farther we go from the centre, the lower 
is the temperature, the greater is the number of electrons 
which a nucleus can retain in bondage, and the fewer and 
less massive are the photons. The process of interchange 
which goes on is nevertheless of essentially the same char- 
acter. When we reach the surface, however, there is a 
change, because many of the photons travelling outwards do 
not meet with nuclei or electrons, and so escape into space. 
They constitute the light by which we see the star and from 
which we have to infer all that we can know about the internal 

This constant escape of photons from the surface of a star 
raises at once the fundamental problem of theoretical 
astronomy. Where do they come from? They can be traced 
back to the centre, which, as we have said, acts as a source 
of heat and consequently of photons for the rest of the star, 
but how is the central supply maintained in view of the 
ceaseless radiation from the surface into space? Photons are 
created when electronic energy is destroyed; hence their loss 
is equivalent to a loss of such energy i.e., to a cooling of 
the star. Nevertheless, there is evidence that the stars remain 
at approximately the same temperatures for at least thousands 
of millions of years. The explanation which seems most 
plausible (though it is not without serious difficulty and is by 
no means generally accepted) is that photons can be created 
by the loss, not only of kinetic energy of electrons but of 
electrons and protons themselves, so that the light which a 
star sends us is its own essential substance. If this is the true 
explanation the stars must be gradually passing away, and 
the Sun, which radiates far less prodigally than the great 
majority of the stars which we see, is losing four million 
tons of itself in every second of time. The figure is startling, 


but there is ample material in the stars to sustain loss at this 
rate over the probable period of stellar existence. 

The mass of a star is from io 27 to 2o 29 tons. Its central 
temperature is a matter of uncertainty, the lower estimates 
being of the order of tens of millions of degrees. A compara- 
tively few "giant" stars, however, may have central tem- 
peratures lower than this. The average density throughout a 
star may be anything from that of the highest vacuum we 
can create to thousands of times that of the densest terres- 
trial material. The variation of density from surface to 
centre, however, is probably in all stars tremendous. The 
extremely high densities, which characterise the white 
dwarfs, are possible because independent nuclei and electrons 
can be pressed into much closer association than organised 
atoms. The space occupied by the solar system, which is 
analogous to an atom, is great out of all proportion to the 
actual volume of its material bodies, and the degree of com- 
pression which would be possible if the orbits were aban- 
doned suggests the extent to which stellar may surpass terres- 
trial densities. The average diameter of a star is of the order 
of a million miles. 

A star, as we have seen, may dissipate most of its sub- 
stance in radiation. There is some likelihood that what re- 
mains may pass eternity as an inert mass having the maxi- 
mum possible density and changing, if at all, only by 
momentary reversible reactions to the radiation of surround- 
ing unexpired stars. The beginning of stellar life offers a 
problem to which the answer, if we cannot properly call it 
more uncertain, is decidedly based on less extensive know- 
ledge. It is customary to contemplate the original state of 
the universe as that of a finite, uniformly diffused nebula 
filling all space, but it must be admitted that the justification 
for this view lies in its harmony with what we like to think 
of as the course of cosmic evolution rather than in any posi- 
tive evidence. The phrase, " filling all space," however, does 
correspond to a definite article of the astronomical creed, 
according to which a finite quantity of matter can be co- 
extensive with space: in other words, astronomical space, 


though it has no boundaries, may be finite in extent and may 
have a definite volume. It is impossible to picture this, and 
useless to try. An analogue is the surface of a sphere, over 
which one may move eternally without reaching a boundary, 
but which has nevertheless a finite area. This, however, like 
all analogies, has a strictly limited application, and breaks 
down if we try to extend it to the inside of the sphere, which 
has no representative in Nature. A year or two ago the prin- 
ciple of relativity seemed to make infinite space impossible, 
but a better understanding of its requirements now shows 
that our present knowledge is insufficient to warrant this 
conclusion. Some astronomers are, nevertheless, convinced 
by philosophical arguments for finite space, but scientifically 
the question remains open. 

It is best not to try to visualise finite space. By exercising 
a strict abstemiousness of imagination we have hitherto ac- 
cepted infinite space without question, although that too is 
beyond mental vision. It is scarcely logical to scorn finite 
space for a quality which its rival equally possesses, and it is 
not easy to see why there should be a universal instinctive 
tendency to do so. Possibly it is but one aspect of a general 
popular revolt against modern scientific concepts which, un- 
like their predecessors, are in general unpicturable by the 
imagination. Space, time, energy and the rest of them no 
longer correspond to the familiar notions we attach to those 
words, but are pure abstractions, having only a rational 
significance. We will not now labour this matter, to which 
we shall return later, but it is well to point out that if the 
modern scientist takes from the ordinary man (as well as 
from himself) the power to picture his concepts, he brings as 
substitute a far more precious gift namely, the power to 
express them in terms of something which can be done. He 
displaces contemplation by action; he no longer says, " Look 
at this," but " Do this," and the new injunction removes the 
possibility of self-deception which was only too easily realised 
under the old. 

The puzzled reader of modern astronomical paradoxes 
should therefore ask himself the question : " To what opera- 


tion does this correspond?" and he can be perfectly sure that 
his question is capable of an intelligible and usually very 
simple answer. Let us ask it of finite space, and we shall get 
the following reply : What is meant by saying that space is 
finite is that if we travel about in it taking, if we like, any 
compass we can devise to guide us always in a straight line 
we shall find that if sufficient time is allowed we shall ulti- 
mately pass through familiar regions again. There will be a 
maximum distance to which we can travel from any specified 
body, such as the Earth, and when we are at that distance, 
no matter in what direction we move we shall inevitably ap- 
proach the body, just as any movement from the north pole 
of the Earth is towards the south pole. 1 This statement of 
something which can be done is not a consequence of the 
conception of finite space; it is the conception of finite space. 
The question, " Why cannot we travel ever further from the 
body?" is meaningless for science, for science never asks, 
"Why?" in such an ultimate way as this. We might as well 
ask why apples fall to the ground and not away from it : it 
is not our business to inquire into such things, but merely 
to record that they do and how they do. The finitude of 
space, if actual, is a quality of nature, not a metaphysical 

Whether space is finite or infinite, however, its character is 
changing. If it is finite the change is accurately describable 
as " expansion " : the sphere we spoke of is like a bladder 
undergoing inflation, so that points stationary on its surface 
are getting farther apart. This reveals itself to observation in 
one of the most remarkable facts of astronomy. It appears 
that the external galaxies with very few exceptions, which 
can be satisfactorily accounted for are receding from us at 
speeds proportional to their distances. Nebulae 43 million 
parsecs away are retreating at more than 1 2,000 miles a second, 
and greater distances, with correspondingly greater speeds, 

1 At present we are not taking into account the expansion of 
space, which is dealt with later. To make this statement true in an 
expanding space we must suppose that we are travelling faster than 
the rate of expansion. 


have recently been measured. 1 The material universe is 
apparently being dissipated, and if the process continues un- 
checked, the time will come when, however greatly tele- 
scopic poWer may be improved, our own galaxy will be all 
that we can observe. We shall not lose that also, for the 
gravitational bond between its stars exceeds the effect of the 
scattering. It is only bodies at the enormous nebular dis- 
tances that are bidding us farewell. 

If our instinct is to ask, "How can space expand when 
there is nothing outside for it to expand into?" we must 
again remember that the idea must be interpreted in terms 
of operations only. Put somewhat graphically, it means this 
and nothing more : if we measure the greatest possible dis- 
tance by which two bodies can be separated, we shall get a 
certain result; if we perform the same operation tomorrow 
we shall get a larger result. There is no need to court in- 
sanity by trying to imagine expansion into a vacuity which 
isn't there. 

If space is infinite, however, we cannot measure the 
greatest distance by which two bodies can be separated, for 
it exceeds all measure. Our operational definition having 
failed, we must therefore conclude that the thing we are 
attempting to define is indefinite. We can say either that 
infinity itself is expanding, carrying its material contents 
with it, or that those contents are separating in an un- 
changing space. For mathematical convenience we prefer 
the former statement, but it has no physical claim to 
priority. The measurements which are interpreted as reces- 
sion of the nebulae are facts, whatever space may be. There 
is a meaning in saying that space may be finite or infinite, 
for the alternatives can be distinguished by conceivable 
observations. But there is no meaning at present in asking 
if infinite space is expanding or not, because it has no in- 
dubitable hall-mark to provide ail observable distinction. 

1 The remarks at the beginning of this chapter concerning the 
meaning of distance and velocity must be recalled here. We need 
scarcely say that for these measurements very indirect methods are 


We cannot leave this point without a warning. Until 
recently we thought gravitational attraction was a uni- 
versal characteristic of matter, because it held sway on the 
earth and among the distant stars. Now that we can 
examine the remote nebulae we find that repulsion is the 
general rule and attraction merely a local peculiarity. In 
forming our ideas of the universe, therefore, we substitute 
repulsion for attraction and proceed very much as before. 
But it would be the height of folly not to learn from our 
mistake that repulsion also may be merely local, yielding in 
still more distant space or future time to some other form 
of interaction. All we say at present about the universe 
assumes of necessity that the region we observe is typical of 
the whole. We must morning and evening remind ourselves 
that that is probably untrue. 

This account of modern astronomy, incomplete and un- 
conventional as in many ways it is, has not been drawn up 
primarily for purposes of instruction. It has been designed 
to present a bird's-eye view of the movement rather than 
the present instantaneous state of the moving body of 
knowledge a fragment of a cinematograph film rather than 
a single snapshot. This would seem to be the treatment best 
adapted to the needs of those who ask such questions as, 
"What is the meaning of it all?" "What lies behind the 
revelations of astronomy?" "What will be the effect of 
recent astronomical discoveries and concepts on our phil- 
osophy of the universe?" It is not at all our intention to 
answer these questions, which everyone must face for himself. 
They are not scientific questions, although scientific know- 
ledge forms an essential part of the data required in answer- 
ing them. All we can do by way of a general approach is to 
clear the ground in order that the questions themselves may 
stand out in the clearest and most significant relief. 

A fact that immediately strikes our attention is that such 
questions as these, which were commonplace associates of 
astronomy a century or more ago, are now almost com- 
pletely divorced therefrom. To give definiteness to the 


point, consider the following extract from the preface to 
a book, famous in its day, entitled The Practical 
Astronomer, by Dr. Thomas Dick. This book, which was 
published in 1845, is not a popular account of the wonders 
of the heavens; it is a detailed technical handbook on 
astronomical instruments, intended for and used by work- 
ing astronomers in the erection and adjustment of their 
telescopes and other appliances. This is what the author 
says : " As this, as well as every other physical subject, forms 
a part of the arrangements of the Creator throughout the 
material system the Author has occasionally taken an 
opportunity of directing the attention of the reader to the 
Wisdom and Beneficence of the Great First Cause, and of 
introducing those moral reflections which naturally flow 
from the subject." 

"Those moral reflections which naturally flow from the 
subject!" Today no astronomer would use such a phrase in 
such a connection. A scientific handbook or a scientific 
paper, as a source of any reflections other than purely 
scientific ones, is absolutely sterile. Yet there has perhaps 
never been a time when progress in astronomy has been 
so provocative of philosophic thought and when so many 
thinkers have turned to astronomy for light on the funda- 
mental problems of existence. How, then, has this re- 
markable change come about? It is not sufficient to point 
to the general secularisation of life and thought, for that 
secularisation is itself mainly due to the development and 
dissemination of scientific ideas. We must look deep into 
the nature of scientific thought before we can find the 
answer to our question. 

I think the answer is at least partly to be found in the 
fact that scientific investigation appears to have undergone 
a change of character though what has actually happened 
is that our understanding of its character has undergone a 
change. The older astronomer was inquiring, or thought he 
was inquiring, immediately into the secrets of creation. The 
sky spread out before him was the veritable handiwork of 
a " Great First Cause," a direct revelation of the power of 


the Creator Who, however much His character might be 
misrepresented by mistaken theologians, was there revealed 
in indubitable terms which none could misconstrue. 

"Nous avons change tout cela." Science today, so far 
from being a revelation of the Divine, is contrasted with 
revelation as a source of knowledge. We do not now study 
direct creation so much as the idols of our own conceiving. 
Where the older astronomer considered a star, we consider 
"Eddington's model" or an "Emden polytrope." The 
Universe, of which he spoke with awe, has given place to 
" the Einstein world " or " the de Sitter world/' which is un- 
emotionally thrown on the scrap-heap when " the Lemaitre 
universe " comes into view. If we wish to understand a sun- 
spot we do not face the difficulties which the observations 
present; we imagine an ideal sunspot from which those diffi- 
culties are absent, and study that instead. The solar chromo- 
sphere, whose secrets our grandfathers sought to pierce with 
telescope and spectroscope, has become a " region of mono- 
chromatic radiative equilibrium," which we explore with 
pencil and notebook. And so throughout the whole of theo- 
retical astronomy. The subject-matter of our investigation 
is not the work of God's fingers but the work of man's 

There is no irreverence in this, nor any betrayal of the 
ideals of science: it is simply a matter of common sense. 
One of the first things a young scientist has to learn is to 
choose his problem to suit the means of investigation at his 
disposal. An amateur with a 3-inch telescope, who set out 
to study the structure of the spiral nebulae, would not be 
consecrating himself to ultimate Truth; he would be acting 
like a fool, wasting on an impossible problem time which 
might be spent with profit on, say, observations of variable 
stars. The modem theoretical astronomer has learnt this 
lesson. His most powerful instrument is mathematics, and 
he therefore chooses for his study problems which can be 
dealt with mathematically more specifically, those problems 
which can be dealt with at our present stage of attainment 
in mathematics. A star as nature reveals it to us is too 


intricate for this, so he imagines a gaseous sphere to which 
he assigns certain mathematically tractable properties, and 
works out the brightness, density and other observable quali- 
ties which such a sphere, if it existed, would have. If those 
qualities approximate to those which are actually observed 
in the stars, the presumption is that his sphere is an ap- 
proximate representation of a star, and the degree and char- 
acter of its shortcoming guide him in making the repre- 
sentation more exact. 

There is, of course, an insidious danger in this. We are 
liable, particularly at periods when our models are unusually 
successful in copying nature, to think that they actually are 
nature. This tendency must be carefully guarded against. 
We have no right to assume that nature, by a self-denying 
ordinance, has limited her phenomena to those which can 
be described by mathematical processes; still less legiti- 
mately can we say that nature, or God, must be funda- 
mentally mathematical because, in studying the physical 
world, we voluntarily restrict ourselves to mathematical con- 

It is necessary to point out this danger, but in truth it is 
not a serious menace to the astronomer; the scientific philo- 
sopher is its most likely victim. The astronomer devotes 
himself confidently to his models and abstractions, not be- 
cause he thinks them reality but because he sees that not 
only they, but also the apparently concrete subject-matter 
of his predecessors, are essentially abstract; that, in fact, 
physical conceptions for the past 300 years have been only 
nominally identical with the actual experiences with which 
they have been associated. The modern attitude of science 
to observation is not a departure from tradition but the un- 
restricted exercise of a liberty which past generations have 
possessed and to some extent employed without realising it. 
Let us examine one or two of the well-known scientific con- 
ceptions prominent in astronomy in order to illustrate this 
general truth. 

One of the most important conceptions of astronomy is 
that of force, by means of which Newton was able to make 


the great generalisation of universal gravitation. Now force 
is a familiar experience, represented, for instance, by the 
pushing of one object against another. Newtonian force, 
however, has nothing to do with pushing or pulling; it is 
defined simply as that which causes a change in the motion 
of a body. If a body is accelerated, Newtonian mechanics 
says that a force is acting on it. A naive student might look 
to see if this is actually so, thinking that perhaps Newton's 
ideas might have been incomplete and that something else 
besides force is capable of changing motion. Such an inquiry 
would be perfectly legitimate, and indeed an obvious one to 
make, if by "force" Newton meant the everyday thing 
which countless generations before him had meant by the 
word. What makes it absurd is that Newton meant some- 
thing essentially different from this. His force was defined 
as the cause of change of motion. Whatever caused such a 
change, whether it was a push or a pull or any other agency, 
was to be called a force, and the whole character and measure 
of the force were embodied in the change of motion. 1 The 
scientific conception of force for the last 250 years has been 
that of Newton, but the interpretation of scientific state- 
ments has usually been in terms of physical sensations. 

Another example is afforded by the conception of a gas. 
What we mean by a gas according to ordinary observation is 
something tenuous, at least partly transparent, spreading 
out to fill whatever space is available for it, a medium 
through which bodies can move with considerable freedom. 
The "gaseous" bodies with which the astronomer deals, 
however, may be far denser than lead, opaque even to hard 
X-rays, exceedingly compact, and as sticky as treacle. The 
explanation of the paradox is that the astronomer's "gas" 

1 Even the notion of cause is not inherent in the Newtonian defi- 
nition. It is actually more accurate to drop this anthropomorphism 
and simply to say that Newtonian force is the change of motion. 
Newton's second law says that force equals rate of change of motion. 
" Cause " is introduced merely to make the process picturable. The 
idea is not used in science, and it is even sometimes more vivid (as 
in the example of centrifugal force) to regard the change of motion 
as causing the force. 


is not defined in terms o observation. It is simply a sub- 
stance composed of hypothetical unit particles whose average 
distance apart is considerably greater than their diameter. 
Yet we have spoken indiscriminately of this substance and 
of air as "gases/' It is necessary to realise that the single, 
common name is justified only if by gas we cease to mean 
the substance corresponding to certain familiar sensations. 
Like force, it is a name long since used in science only as 
denoting an abstract idea. 

Examples might be multiplied ad lib. The model of 
the universe which astronomy has been building up since 
the time of Galileo is an ideal one, constructed of bricks 
made from rational conceptions, not from sensible experi- 
ences. The open acknowledgment of this fact, made during 
the last decade or so, is the result not of a revolution in 
method but of a clearer understanding of what has been 
done in the past and a greater freedom in employing con- 
ceptions which have no obvious analogues in experience. 
The exercise of this freedom is the source of much of the 
difficulty met with in trying to understand recent develop- 

It must be admitted, however, that the confusion arising 
from this discrepancy between the direct mental representa- 
tion of immediate experience and the more abstract con- 
ceptions of science (which, in its general form, is simply 
the familiar confusion of calling different ideas by the same 
name) is not peculiar to the layman. For the scientist also 
there are dangers in the gradual change of significance of an 
idea with increasing abstraction, in that earlier and later 
stages in the development of a conception may be unwit- 
tingly regarded as identical because they bear a common 
name. There is an interesting situation at the present time 
which possibly exemplifies this; namely, the inconsistency, 
already referred to, between the implications of different 
definitions of time. One line of thought in which time is 
involved gives our stellar system an age of something like 
io 13 years. Another line of thought makes the whole uni- 
verse much younger than this. The task of tracing back the 


intricate lines of argument to see precisely what is meant 
by " time " in each case is an extremely difficult one, but it 
may have to be undertaken. The only thing which is clear 
now is that unless the universe is fundamentally irrational, 
different definitions have been used and it may be added 
that neither of them corresponds in all respects with our 
usual notion of time. The reconciliation of the results may 
have wide implications. 

We are, then, to regard as the most significant feature of 
modern astronomy the realisation which it brings of the 
nature of astronomical conceptions. We see that those con- 
ceptions, which have in the past been identified with ex- 
periences drawn directly from our contact with the external 
world, are in reality creations of our mind, whose function is 
to correlate our various observations and so make the world 
rational in other words, to make a rational universe out of 
diverse phenomena. In the limited field of observation open 
to us in the past, the differences between scientific concep- 
tions and the corresponding familiar notions have been in- 
conspicuous, so that their existence has been widely over- 
looked. The great extension of observational astronomy in 
the last few decades, however, has made fresh demands on 
the conceptions, in fulfilling which their divergences from 
familiar notions have been glaringly exposed. What we 
thought were direct revelations of nature we find to be our 
own inventions not arbitrary inventions, it is true, for we 
choose them in order to give coherence to facts given us in 
observation, but nevertheless inventions which further ex- 
perience may force us to modify perhaps beyond recognition. 
We thought them facts which were eternal, and we find 
them ideas which are transient, or at least protean. 

These considerations, which will be extremely disconcert- 
ing to those who expect to find in astronomy an immediate 
revelation of a wonderful and unique universe, are presented 
without apology, for they represent actually what astronomy 
is concerned with today. The change, compared with the 
aspect of astronomy in former times, is great, although, as 
we have said, it is only skin-deep. But it will be objected : 


"You have spoken only of theoretical astronomy, of our 
interpretation of the facts; what of the facts themselves, re- 
vealed to us by direct observation? Are they not being dis- 
covered now as formerly, and do not they reveal to us some- 
thing not ourselves which speaks of a Power behind nature?" 
True, observational astronomy is not languishing. It is the 
source and has the control of all our theories, and it is being 
prosecuted today with a vigour and on a scale undreamed of 
a hundred years ago. But alas ! it is no longer the observa- 
tion our great-grandfathers knew; it is something which 
itself depends scarcely less on interpretation than the theories 
which it originates. When Herschel discovered the planet 
Uranus he saw its surface with his own eyes, and observed 
its movement among the fixed stars. Pluto was discovered 
by the change of position of a spot on successive photo- 
graphic plates taken as the result of mathematical calcula- 
tions made many years ago. Halley discovered the move- 
ment of the stars by observing directly that their positions 
in the sky were no longer those observed 1,800 years pre- 
viously. We discover the movement of a spiral nebula by 
measuring the positions of marks on a tiny rectangular 
smudge on a single photographic plate. Almost the whole of 
observational astronomy today consists of marks on photo- 
graphic plates which are quite unintelligible to the un- 
initiated, and require the application of physical theory 
before they become the data used by the theoretical astrono- 
mer. All that can be discovered by direct observation is 
already known. 

And so we see why astronomers no longer discourse of 
" those moral reflections which naturally flow from the sub- 
ject." They are too modest. They realise that whatever 
grandeur belongs to the universe they picture is a grandeur 
of their own creating, and they hesitate to proclaim it. 
Doubtless they are right in this, for otherwise they could 
hardly avoid misunderstanding. But at the same time, from 
a thoroughly impersonal point of view it would perhaps ap- 
pear that there is no less cause than formerly for reflection 
on the meaning of scientific progress. If modern astronomy 


reveals to us more of the nature of our minds than of the ex- 
ternal world, is the exchange so much to be deplored? For 
it is not the arbitrary, capricious, personal elements of our 
minds that are embodied in astronomy; they can be left to 
psycho-analysis to do with them what it can. Astronomy ab- 
sorbs the universal, impersonal factors which form the sub- 
stratum of mental life. The universe we contemplate today 
may disappear tomorrow, but it represents a mental nexus 
between the diverse facts of present experience which is not 
the whim of a single astronomer, but one of a few alterna- 
tives forced on all by the nature of logical thought. That is 
surely not without meaning. 

The scientist is sometimes regarded, in contrast with the 
poet, as a dull, mechanical being, who looks at nature with- 
out emotion and sees only dead logic in the living garment 
of God. "When I heard the learn'd astronomer," wrote 
Whitman, "how soon, unaccountable, I became tired and 
sick; till, rising and gliding out, I wander'd off by myself in 
the mystical, moist night-air, and from time to time look'd 
up in perfect silence at the stars." But in truth it is a shallow 
nature which can draw emotion from the skies at will as one 
draws water from a fountain, and the experience has little 
ultimate value. The astronomer in his nightly or daily work 
is not as a rule entranced with the wonder of things. He re- 
gards the stars in the matter-of-fact way which is essential to 
the proper performance of his work, and is no more over- 
come with rapture than is a surgeon with pity. But to him, 
as to others, there come rare moments when the familiar 
suddenly and imperceptibly takes on an unfamiliar appear- 
ance, when thought becomes strangely clear, and the finite 
seems to open out into the infinite. It may be that such 
moments come less frequently to the astronomer than to 
those who have no scientific interest in the sky, but can it be 
doubted that when they do come their content is greater and 
their value deeper and more lasting from the knowledge, felt 
rather than thought, that the universe is no chaos but that 
all its diverse elements are bound together into an ordered 
whole by the stuff of which man's mind is made? 



Professor of Mathematics in Harvard University 

THE extent of general intellectual interest in mathe- 
matics has varied in different periods of human 
thought. It has always been acknowledged that 
mathematics is of basic importance because of its applica- 
tions. But whether it is to be regarded merely as the useful 
handmaid of the sciences or as the queen of the sciences has 
been a matter of considerable dispute. On the one hand, we 
find the common ' practical ' attitude of which Newton com- 
plained to Halley in a letter of 1686 : 

" Now is not this very fine? Mathematicians that find out, 
settle, and do all the business must content themselves with 
being nothing but dry calculators and drudges; and another 
that does nothing but pretend and grasp at all things must 
carry away all the invention. . . ." 

On the other hand, there is the feeling of Pythagoras, Plato, 
Descartes and other lofty spirits that somehow mathematical 
thought furnishes the master-key to philosophic insight. 

The advent of the present century ended a period in which 
the range of both pure and applied mathematics had been 
enormously extended. Thus in his History of European 
Thought in the Nineteenth Century Merz concluded that 
progress in the several fields of science had been more or less 
proportionate to the extent to which mathematical methods, 
had been introduced : " . . . through the increasing applica- 
tions of mathematical methods of measuring and calculating, 
our thought has become truly scientific. . . ." Nevertheless, 
the general attitude was one which conceded a fundamental 
practical value to mathematics rather than one which admired 


its beauty and profound significance. This fact was evidenced 
by contrast. An astronomical, physical, chemical, or bio- 
logical discovery was hailed, not only by the specialist, but 
by the philosopher, the theologian, and intelligent layman as 
well, for all felt that new insight of first importance was there- 
by gained. But such an epoch-making mathematical dis- 
covery as that of the transfinite numbers of Georg Cantor, 
which would doubtless have been appreciated to the full by 
the ancient Greeks, remained for a long time unnoticed even 
by the philosophers. 

Today, however, the situation is strikingly different. It is 
generally felt that mathematical thought possesses a funda- 
mental significance not yet wholly understood, and Plato's 
mystic conjecture that the Deity 'geometrizes continually' 
is repeated in new forms by Jeans and others. 

The principal factors which have led to this revival of 
interest are easy to trace. Of dominant importance has been 
the formulation of Einstein's special or electromagnetic 
theory of relativity of 1906, and of his general or gravita- 
tional theory of 1915. Both broke in rudely upon a previously 
almost unquestioned dogma of human thought namely, 
that of absolute simultaneity and absolute time. 

The effect thereby produced can scarcely be over-estimated. 
It had been the fondest hope of the mechanistic physics to 
show that the physical world was in essence only a puppet- 
show of a very particular kind namely, one in which the 
puppets were * rigid elastic spheres' and similar idealized 
objects, held together by idealized ' weightless springs,' while 
the stage was to be that of Euclidean space and absolute time. 
And now the relativistic theories demanded a new stage on 
which these time-worn puppets could not even appear. Thus 
the new theories upset those of classical physics completely, 
as far as any hope was concerned of furnishing a final picture 
of physical law, although the approximate truth of the old 
formulations was not affected, of course. 

The theories of relativity were predominantly mathe- 
matical in that their adequate comprehension involved the 
well-known geometric theory of Riemann concerning geo- 


metrical spaces of n dimensions and the absolute differential 
calculus of Ricci and Levi-Civita both purely mathematical 
theories. In fact, the fundamental idea of the gravitational 
theory of relativity undoubtedly occurred to Einstein in the 
form of a mathematical question : " Might not the paths of 
particles (planets or light-beams) about the sun be merely the 
shortest paths in a semi-flat, four-dimensional Riemannian 
space-time?" And in order to answer this question Einstein 
found it necessary to learn and apply the fundamental tech- 
nique of the absolute differential calculus. The numerical 
result of his calculation supported the correctness of the con- 

Thus it is certainly not exaggerating the case to say that, 
without the purely mathematical ideas of Riemann, Ricci, 
and Levi-Civita, neither the special nor the general theory of 
relativity could have taken form. 

Physicists and astronomers have not always been as for- 
tunate as Einstein in finding mathematical theories ready 
made for their needs. Kepler had sound ideas about the role 
of gravitational force in the solar system, but he lacked the 
necessary mathematical tools to develop them namely, the 
analytic geometry of Descartes and the infinitesimal calculus 
of Newton and Leibnitz. Newton himself had to invent the 
calculus in order to be able to work out the consequences of 
the suspected gravitational law. Faraday's experimental 
genius required to be supplemented by the mathematical 
genius of Maxwell and Hertz before the full consequences of 
Faraday's work could be seen; and it is by this curious path 
that the ' radio ' has come into existence. 

Since 1915 the mathematical demands upon the physicist 
have been constantly increasing through a succession of 
" mathematical theories " which, Bridgman says, " are being 
continually formulated at an ever-increasing tempo and in a 
complexity and abstractness increasingly formidable/' No 
one doubts that these theories of Bohr, de Broglie, Schro- 
dinger, Heisenberg, and Dirac are of the utmost significance, 
but the predominant role of purely mathematical framework 
is apparent. As Dirac has phrased it : 


"... Mathematics is the tool specially suited for dealing 
with abstract concepts of any kind, and there is no limit to 
its power in this field. For this reason a book on the new 
physics, if not purely descriptive of experimental results, must 
be essentially mathematical. 

" . . . The only object of theoretical physics is to calculate 
results that can be compared with experiment, and it is quite 
unnecessary that any satisfying description of the whole 
course of the phenomenon should be given." 

Thus purely mathematical processes have taken a position of 
central importance, leaving the average physicist, however, in 
a very uncertain frame of mind. 

As an indication of this situation, I recall a series of five 
lectures given within a few years by a distinguished physicist, 
in which he proposed to expound his new theory. What was 
my surprise to find nothing but classical mathematics pre- 
sented in the lectures, dressed up, it is true, in an alluring 
garb of physical terminology. As far as I could observe, my 
somewhat bewildered friends the physicists were entirely 
satisfied. Of course, this was because they were eager to gain 
an appreciation of the mathematical processes which mys- 
teriously ground out the right answers at the end. 

A possible danger is that, with the infinitely varied re- 
sources of modern mathematics at the disposal of the theorist 
in physics, and with no specific limits set to his hypotheses, 
he can always devise an ad hoc mathematical machine which 
will do whatever is required. But this danger, if such it be, is 
altogether outweighed by the advantages of ceaseless and 
daring mathematical formulations which aim to explain and 
predict in the weird domain of atomic physics. 

Thus the aggregate effect of recent advances in physics has 
been to bring about the general conviction that the under- 
standing of final law in the physical universe will turn out to 
be a mathematical understanding rather than one in which 
ordinary physical concepts and intuitions play the chief role. 

Of this truth the mathematician hardly requires to be 
convinced. He may be compared to the mining geologist, 
who is primarily interested in important mineral deposits, 


wherever they may exist, and who cannot think even of sea 
water without realization of its mineral content. Likewise 
the mathematician, these many centuries, has been searching 
for logical structure and finding it everywhere. All physical 
phenomena suggest to him ' differential equations ' or other 
equations which embody their fundamental quantitative 
laws. But, equally, all biological, psychological, and social 
phenomena seem to him to reveal logical structure, however 
rudimentary in character, and he must believe that deeper 
progress in these more difficult directions can only be realized 
when suitable mathematical concepts and methods have been 
devised. Furthermore, the vast domain of purely mathe- 
matical thought forms for him irrefutable testimony that the 
subjective as well as the objective world is mathematical. 
Thus with Descartes he will declare Omnia apud me mathe- 
matica fiunt With me everything turns into mathematics. 

While recent physical advance has been the principal 
reason for the renewed interest in mathematics, another 
cause of less importance from the practical point of view, but 
perhaps equally significant at bottom, must be mentioned. 
The philosophers, who long regarded logic as part of their 
especial domain, realize today that logic is coextensive with 
mathematics; for, according to the American mathematician 
Benjamin Peirce, "mathematics is the science which draws 
necessary conclusions." It might appear that rigorous deduc- 
tions could be found in non-mathematical domains. George 
Boole, the Irish mathematician, tells us, however, that, in 
trying to find an example of a syllogistic chain of reasoning 
(not of the obvious Aristotelian type) to illustrate his symbolic 
logic, he searched in vain through the work of that most 
mathematically minded of philosophers, Spinoza. 

Thus mathematics is the codified body of all logical 

What is the inner secret of mathematical power? Briefly 
stated, it is that mathematics discloses the skeletal outlines of 
all closely articulated relational systems. For this purpose 


mathematics uses the language of pure logic with its score or 
so of symbolic words, which, in its important forms of expres- 
sion, enables the mind to comprehend systems of relations 
otherwise completely beyond its power. These forms are 
creative discoveries which, once made, remain permanently 
at our disposal. By means of them the scientific imagination 
is enabled to penetrate ever more deeply into the rationale of 
the universe about us. 

There has been a fundamental effort on the part of those 
interested in symbolic logic to give it a purely mechanical 
form. This has been a natural aim suggested by the pioneer 
work of Boole on that subject, in which he shows that sym- 
bolic logic is a kind of algebra in which the only two symbols 
of quantity are o and i. 

Thus it has been sought to make logical reasoning as 
definite and precise in its rules of manipulation as the game 
of chess, with which it may be compared as follows : The 
assumed propositions or hypotheses correspond to a given 
initial ' position ' of the chessmen; the * moves ' are then 
the ones allowed in the logical game in passing to other more 
complicated propositions, and the game is won when the 
desired final proposition is arrived at in this manner. 

Unfortunately, this alluring goal of logical mechanization 
has not yet been effectively reached. Indeed, in chess itself 
there are moments when the arbitrary inaccurate judgment 
of an umpire is required to determine whether or not a move 
has been initiated or not, whether a time limit has been ex- 
ceeded, or whether a game is a draw; and it is even conceiv- 
able, although entirely unlikely, that some possibility not 
foreseen by the rules of chess might arise. In symbolic logic 
much more formidable difficulties exist which stand in the 
way of its effective reduction to a genuinely mechanical game. 
There are three of these difficulties to which I will refer 

The first is occasioned by the fact that the meaning of a 
logical statement is not entirely independent of what precedes 
it; in chess, on the contrary, a player can continue the game 
from a specified position without any regard whatsoever to 


what has taken place earlier. If this dependence of logical 
meaning upon what has gone before is ignored, queer logical 
paradoxes result; for example, the following well-known one. 

All integers admit of being defined in a finite number of 
words (of the English language). We may name the least 
integer not definable in less than one hundred English words. 
This is a perfectly definite integer, since there are only a finite 
number of combinations of less than one hundred words. 
But it has just been defined in only eleven words! 

The inherent difficulty may be elucidated as follows. For 
definiteness let us select some particular dictionary in which, 
of course, certain integers, as one, two, . . . thousand, million, 
etc., appear as words. These are definable in two words, such 
as the integer three, for instance. Thence we proceed, step 
by step, to collections of three, four, and more words, striking 
out those collections which are not satisfactory English defi- 
nitions of an integer. Theoretically at the end of many, 
many aeons ! all the combinations of less than one hundred 
words will have been used up, and a certain extremely 
numerous set of integers will have been defined. We then 
proceed to list these numbers in order of magnitude 

and we observe the first gap in the series. This occurs at the 
least integer not definable in less than one hundred words. 

But with this series in mind as already obtained, only 
eleven words are necessary to define this interesting number ! 
And this same sequence of words will have been rejected 
earlier as not furnishing a satisfactory definition ! 

The obvious conclusion is that the meaning of a logical 
statement may depend vitally upon what has gone before. If 
this fact be ignored, all sorts of logical confusion are certain 
to arise. 

The theory of the ' hierarchy of types ' in symbolic logic 
was designed by Russell and Whitehead precisely in order to 
eliminate this dangerous source of confusion and contradic- 
tion. It has been largely successful in doing so, but since, as 
each successive logical type is defined, an independent new 


logical act is required, the logical theory so obtained can 
hardly be regarded as a purely mechanical one. 

There is also a difficulty in disposing of the following 
question : " How far is choice by * nat ' allowable as against 
choice by ' definition'?" If, for instance, I say, " Let an arbi- 
trary correspondence be set up such that to any integer there 
is a corresponding unique prime integer/' I am proceeding 
by 'fiat/ and I have no logical qualms in this case; for have 
I not an infinitude of prime integers to draw on namely, 
2 >3> 5 7> ll > *3> - and can I not take them arbitrarily one 
at a time to correspond to the successive integers? But there 
is no necessity for proceeding by fiat in this case, for I can 
make the nth prime in order correspond by ' definition ' to 
the nth integer as follows : 

Now in more complicated cases the second way of choice 
by definition is not open. For instance, if I consider all (finite 
or infinite) collections of numbers between o and i i.e., all 
sets of numbers like 0*361785 . . . where the figures 3, 6 ... 
are taken arbitrarily, I can by fiat select one representative 
number out of each one of this colossally infinite set of col- 
lections but I can never do so by definition I 

Evidently the act of choice by means of explicit definition 
is much more realistic than that made only by fiat, and it is 
found that there exist remote domains of mathematical 
thought which are valid or not according as we allow choice 
by fiat or require choice by means of a constructive definition. 

Thus those esoteric parts of mathematics in which ex- 
tremely elaborate choices enter are still in a state of much 
vagueness. Fortunately, however, if we remain in the 
ordinary domains of mathematics, these difficulties never 
enter, since choice by definition always suffices. 

Here, then, is a difficulty in symbolic logic as to the extent 
of allowable choice, on which opinions of competent mathe- 
maticians actually differ. 

A third difficulty is one concerned with the nature of the 
integers, considered from the purely logical point of view. 


Russell and Whitehead, following the German mathema- 
tician Frege, would make of the integer and so of all numbers 
a logical ' construct ' based upon the logical relation of one-to- 
one correspondence of classes. How natural this attempt is 
appears from the fact that numerically equal classes are pre- 
cisely those which may be matched in one-to-one correspon- 
dence. Thus I can make each finger of my right hand touch 
the corresponding finger of my left hand, because there are 
five fingers in each hand. 

Unfortunately, the notion of the integers is so deeply in- 
trenched in our very use of the symbols of logic that it is not 
clear whether number may safely be regarded as a purely 
logical ' construct/ The great German mathematician Hilbert 
takes in the integers as a basic part of his logic, and thus 
avoids a possible vicious circle. 

It will be seen that these difficulties, referring to the 
frontiers of symbolic logic, do not threaten the validity of the 
main body of accepted mathematical thought. Whatever the 
final outcome, nothing is to be anticipated which will affect 
the principal syllogistic chains thus far discovered, although 
certain remote types of 'transfinite reasoning' may be im- 

As might be expected, however, in this day when every 
dogma is questioned, there have been attempts to detach 
logic from its apparently secure position. Since we have been 
able to invent non-Euclidean geometries, and to unite space 
and time, why should we not invent non- Aristotelian systems 
of logic quite as interesting and self -consistent as Aristotelian 

It was the Dutch mathematician Brouwer who first pro- 
posed a system of ' intuitionist logic,' in which a proposition 
may be true, or false, or neither true nor false, thus denying 
the accepted principle of tertium non datur. 

Now it is conceivable that some mathematical facts may 
not be demonstrable. For instance, it is exceedingly probable 
that, in the well-known number 

^ = 3-1415926 . . ., 


the sum of the first n figures divided by n tends to approach 
4-5 (the average of the ten digits o, 1,2, 3, 4, 5, 6, 7, 8, 9). For 
why should not there occur in the long run approximately as 
many of each of the ten digits? In fact, if we compute the 
average of the first twenty-five digits occurring, we obtain 
472, which differs from 4-5 by less than 5 per cent. 

But in the present state of mathematical science no one 
knows of any method for proving that the average does tend 
actually towards 4-5. If this conjecture should be true, but 
not demonstrable, we could never be certain of the fact by 
means of any computation of the successive averages, how- 
ever extensive, since there might exist an unexpected distri- 
bution of the later digits. 

There are two attitudes which might be taken in this 
event : 

(1) The asserted law of averages is regarded as true though 
not demonstrable. 

(2) The asserted law of averages is regarded as neither true 
nor false. 

If we adopt the second point of view, which is Brouwer's, 
we are, in my opinion, adopting an unnatural form of ex- 
pression which puts mathematics into a kind of straitjacket, 
and renders it less attractive; and, furthermore, we are not 
thereby bringing out essentially new facts. 

After all, mathematics consists in the discovery and clear 
codification of genuine and important syllogistic chains of 
reasoning. Any scrupulously honest result in this direction 
can be depended upon to have permanent value, even 
although a more precise form of statement may be discovered 
later on. In this connection I am reminded of a mathematical 
paraphrase once used by the American mathematician E. H. 
Moore : " Sufficient unto the day is the precision thereof." 
The final day of maximum precision of logical thought has 
not yet arrived, and that day may be long delayed. By what 
peculiar means such precision is to be attained cannot be 
forecast in advance. Suppose that I assert that my friend A 
was in England on a certain day. As far as this assertion is 
concerned, he might have been just entering England over 


the Scottish border at midnight of that day. However, if I 
assert A was in England on a certain date, and in fact was in 
Cambridge at noon of that day, the precision of my first 
assertion is made absolute by means of another assertion 
which in itself is not wholly precise ! Likewise it may turn 
out that the ultimate form of symbolic logic will carry with 
it the use of auxiliary propositions whose truth or falsity is 
not wholly clear. Perhaps, in some such sense as this, there 
may be a certain kind of validity in Brouwer's affirmation 
that a proposition may be neither true nor false. 

It has been remarked above that the forms of mathematical 
expression and in particular its special symbolisms must 
be regarded as discoveries of fundamental importance; the 
alphabet is a symbolic discovery of similar type whose im- 
portance likewise cannot be over-estimated. In general the 
chief function of mathematical symbolism is to enable the 
human mind to carry through certain processes of logical 

While the mind in its logical workings starts from a few 
extremely simple ideas corresponding to the terms of the 
primitive logical language, it is soon found that certain 
natural groups of these ideas and terms constantly reoccur. 
Thus, with or without the intervention of special creative in- 
genuity, there arises the habit of treating such groups as a 
unit and of naming them by special symbols. 

This process is strikingly analogous to that by which atoms 
are formed by the natural aggregation of protons and elec- 
trons, or crystalline structures out of atoms. Here we may 
revert once more to our mineralogical analogy and compare 
the varied natural forms of logical structure to the crystalline 
forms of mineral structure. 

It is in this way that the numbers the most important 
special symbols of mathematics inevitably arise. The main 
phases are as follows : (i) The use of special marks (integers) 
instead of counters, for convenience in counting; as, for in- 
stance, the use of one large stone instead of ten small ones, in 


counting a herd of animals; (2) the use of special marks and 
positions to indicate addition, subtraction, etc.; (3) the codifi- 
cation of general laws, using algebraic marks (letters) to stand 
for any number, thus leading successively to the fractions, 
zero, the negative numbers, and finally the so-called imagin- 
ary numbers involving the symbol >/ i ; (4) the observa- 
tion that the process of extension terminates naturally at this 
stage. The full justification of the complete number system 
under the general laws of operation can be made without 
much difficulty, so that to any person with a fair mathe- 
matical training the term 'imaginary' seems a misnomer 
when applied to the so-called imaginary numbers. The sim- 
plest means of making such a justification is by means of a 
geometrical representation of these numbers and the opera- 
tions to which they are subject. 

A particularly simple illustration of this general evolu- 
tionary process is the following : The algebraists were in the 
habit of writing a quadratus for the square of a, with like ex- 
pression for the cube of a, etc. Then for brevity they jotted 
down a 2 or a 3 instead, or similar expressions, putting the 2 or 
3 in special position to indicate that it was not a factor but a 
power. la this way they passed insensibly from obvious 
special laws such as 

a 2 x a* = 

to the corresponding general laws such as 

S*YI\. vx sii\ __ siH\ "f* n 
U /\ U ^^ Cl 

But this suggested automatically the question as to what a, 
a" 1 , ... represent, and also the inevitable answers; for evi- 
dently we have a 2 = aa, a 1 = a, a = i , a' 1 = i -f- fl, etc., when we 
divide by a successively. In the same way the query as to the 
meaning of d> arises. But by the above law the following 
equation must hold : 

x ( 

whence it was concluded that a* must be the square root of a. 
This is a typical instance of the characteristic natural pro- 


cess at work in the elaboration of symbolic forms : the mean- 
ing of apparently meaningless combinations of symbols is 
sought in the light of the known formal laws of manipulation. 

From the practical point of view the importance of a 
thorough exploitation of the formal domain is obvious. Only 
by complete mastery of it are we able to provide the varied 
symbolic forms which are required in applied mathematics. 

At this point it is desirable to recall why the notion of 
' function ' is a most important one in the applications of 
mathematics, and also to point out that this notion is inherent 
in the formal domain of number just referred to, without 
regard to any such applications. 

If x is a generic symbol for a number that may have any 
value, then x is called a ' variable.' Now it may happen that 
a second variable y is determined when x is given. For in- 
stance, the distance, y, which a body falls from rest in a 
vacuum depends on the time elapsed, x; in fact, we have the 
functional relation y=i6x 2 very nearly, if x and y are 
measured in seconds and feet respectively. In this case y is 
said to be a ' function ' of x. 

It is obvious that mutually dependent physical variables 
are found everywhere in nature, so that the notion of function 
is fundamental in the applications of mathematics. But it is 
also easy to justify our assertion that the notion of function 
arises naturally, regardless of any application. For example, 
we know, by ordinary ' long division/ that 


- = 1 1 1 1 J ... 

But since there is no especial virtue in the base 10 of our 
decimal system as against any other base x, we conjecture 
and prove that in general 

-+ 4.L 

" .. i J2 i .,3 

]~ o |^ q . 

X - I X X 2 X 3 



In other words, we find it desirable to introduce variables 
in order to express a general truth, rather than arbitrary 
special manifestations of it. This explains why the language 
of functions is the natural one in dealing with the domain of 

The vast array of general relationships of the above type 
is called analysis by mathematicians, and constitutes one of 
the major divisions of pure mathematics, along with geome- 
try, algebra, and arithmetic; it will be understood, of course, 
that these terms are to be interpreted in an extremely broad 
sense. No one of these divisions in its full extent can be 
traversed by any single mind ! 

If one asks what these numbers and other similar symbols 
really are as, for instance, what is the number 2 only 
one answer can be given: Such symbols are the abstract 
marks representing specific collections of other symbols or 
things. Thus the number 2 is a special mark which desig- 
nates the class of the letters A, B, or any other class in one-to- 
one correspondence with it (as C, D, or the sun and moon). 
Our strong feeling that the number 2 exists springs from the 
fact that we can operate with the mark 2 much as we do with 
any other objective thing because its properties are absolutely 
clear and permanent. 

There are other kinds of marks besides those of the 
ordinary real or imaginary numbers which the mathematician 
considers as ' numbers ' for instance, * hypercomplex num- 
bers/ 'modular numbers/ 'ideal numbers/ and the 'trans- 
finite numbers' of Cantor. Such symbols are considered to 
be numbers because they satisfy nearly all of the require- 
ments obeyed by ordinary numbers. 

Concerning the first three types of numbers mentioned it 
may be remarked here that it is possible to represent such 
numbers explicitly in terms of ordinary real numbers, just as 
the ordinary imaginary numbers can be so represented. Fur- 
thermore, these three types of numbers have many important 
applications. In fact, the 'matrices' of the recent physical 
theories of Heisenberg and Jordan are essentially hyper- 
complex numbers. For these number systems the ' commuta- 


tive law of multiplication ' ab = ba fails to be generally true, 
but all the other laws hold. 

The fourth transfinite type of number is the most interest- 
ing of all from a philosophic point of view. These arise as 
follows : The integers are the marks for finite classes; for a 
long time the mark oo has been applied to classes possessing 
an infinite number of objects, such, for instance, as the class 
of all integers i, 2, 3, etc. Thus the marks or numbers 
attached to discrete classes have been 

i, 2, 3, ... and oo. 

Now Cantor observed that some infinite classes are really 
more infinite than others. The test for equality of infinities 
is naturally the fundamental test of one-to-one correspon- 
dence; thus there are as many even integers as there are in- 
tegers, as the following one-to-one correspondence shows : 

1, 2, 3, 4 ... ad inf., 

2, 4, 6, 8 . . . ad inf., 

in which each integer is made to correspond to its double. 
Likewise it may be proved that, contrary to first expectation, 
there are as many fractions -|, ~|-, |, , \, etc., as there are 
integers. This kind of infinity is called a ' countable infinity/ 
More specifically, Cantor proved that the aggregate of all 

I J 1 OO O 

positive numbers less than i forms a larger uncountable in- 
finity, and his proof is almost instantaneous. If all the num- 
bers between o and i could be counted off in order that is, 
written in a countable succession, as a, b, c, etc. we would 
reach a contradiction as follows : Form a decimal sequence 
of digits whose first figure after the decimal point differs from 
that of a, whose second figure differs from that of fo, and so 
on indefinitely. This stands for a number less than i and not 
equal to any in the sequence a, b, c . . . since its digits are 
not all the same as those of a, or of b, or of c, etc. Hence not 
all of the numbers can be listed in such a countable sequence 
a, b, c, . . . 

Thus infinite classes may be classified according to their 
degree of infinitude, and assigned corresponding marks, the 


so-called transfinite cardinal numbers, of which the countable 
infinity is the least. However, only a countable set of these 
transfinite cardinals can be assigned definite marks, since 
only a countable set of marks is at our disposal. The similar 
transfinite ordinal numbers of Cantor play a fundamental 
part in the theory of logical types of Russell and Whitehead. 

When we observe any class of phenomena, certain ' unde- 
fined elements ' are in general found to be significant, as well 
as certain 'undefined relations' between these elements. 
These elements and relations are left undefined because we 
cannot define all our terms without involving a vicious circle, 
and so there must always remain a certain set of elements 
and relations which are taken for granted. 

As soon as the ' postulates ' or fundamental laws involving 
these elements and relations are known we feel that we under- 
stand the phenomena in question. In particular we expect to 
be able, with the aid of mathematical reasoning, to deduce all 
further facts and to make any desired predictions. The 
mathematical body which results is called an abstraction. 

The number system itself affords a very important instance 
of an abstraction. Here the elements are numbers; the rela- 
tions are those of equality, etc., while the postulates are such 
laws as a + b = b + a, etc. Likewise the geometry of Euclid, 
with points and lines for undefined elements, with various 
undefined relations such as that a point lies on a line, and 
with postulates such as the 'parallel postulate/ forms an 

The creative mathematician is very skilful in the modifica- 
tion of abstractions. Thus from Euclidean geometry he has 
passed to the more general non-Euclidean geometries by 
omission of the parallel postulate, and similarly he has de- 
vised other kinds of geometry. In the same way he has in- 
vented various number systems of much interest and im- 
portance, as has been pointed out above. The prototypes of 
the abstractions of mathematics are suggested by everyday 


experience and by the various domains of experimental 

An instructive instance of how abstractions may arise in 
the most unexpected manner is the following. According to 
the Constitution of the United States of America, each state 
is entitled to a number of Representatives in Congress (at least 
one) proportional to its population, the total number of Repre- 
sentatives being determined by law. But this constitutional 
requirement cannot be carried out exactly, of course. The 
question, then, arises as to how it can be carried out with 
least injustice to any of the states. Thus there begin to arise 
' elements ' : the conceivable populations of the states together 
with possible assignments of representatives. Furthermore, 
of two elements with the same populations but different 
assignments one is to be thought of more just than the other 
a ' relation ' between two elements. Finally, there are cer- 
tain natural postulates which present themselves, as, for in- 
stance, the following: In the best possible assignments for 
given populations of the states the larger of two states should 
receive at least as many representatives as the smaller. Thus 
by a careful analysis, which cannot even be indicated here, 
my colleague Professor Huntington has succeeded in deter- 
mining the * best ' method of assigning representatives in any 
case whatsoever (that designated by him as the method of 
the ' harmonic mean '), and he has compared it with other 
rival methods, including the one in actual use. 

His primary contribution seems to me, however, that he 
has shown how, in the difficult social domain, the choice 
between different conclusions may hinge upon a slight differ- 
ence in sets of underlying postulates, both of which appear 
equally reasonable or nearly so. From this simple illustration 
it is suggested that mathematical abstractions may prove of 
vital importance at the social level, where their chief role is 
likely to be one of clarification and classification. 

Pythagoras first made the conjecture that the physical 
world is governed by mathematical law. In this way he fore- 


saw a fundamental truth which innumerable researches in 
the physical sciences since his day have established in detail. 
His starting-point was given by a few simple laws obeyed by 
musical strings, and by the earth, sun, and planets; but these 
were sufficient to lead him to a conclusion which lay far 
beyond the vision of his contemporaries. Such moments of 
insight justify our utmost efforts to obtain as wide a philo- 
sophic outlook as possible. 

At the present time we are confronted with innumerable 
known facts codified in many important laws, and more and 
more of these are continually being accumulated. No one 
mind can hope to grasp the immense array. We are over- 
whelmed by an avalanche of increasing knowledge, and it is 
essential for the welfare of our spirit that we obtain a better 
understanding of the nature of knowledge, just as it was im- 
perative in the time .of Pythagoras that the human spirit 
should gain some appreciation of the ordered regularity of 

This quest for deeper understanding is a difficult one, of 
course. It is part of the purpose of these essays that specialists 
in diverse fields of science should express themselves in what 
may be called the Pythagorean manner in so far as they feel 
justified in doing so. In order to share in the fulfilment of 
this purpose, which seems to me of interest and importance, 
I shall indicate some of my own general conclusions. 

The world in which we live is permeated with structure, of 
which we have not yet begun to realize and perhaps never 
can realize more than an infinitesimal part. A glance at the 
external world and also at the world within suffices to con- 
vince me of this fact. It is even possible that the structure 
outside and inside are intimately related at least, it is only 
by means of our mental processes that we succeed in con- 
trolling the external world. 

It is very natural, then, to examine the nature of the struc- 
ture of thought. Here, as has been said above, the central 
fact is that there is structure only in so far as it is logical or 
syllogistic structure. In fact, in the gathering of experience 
we learn that A implies B : the child who comes too near to 


the fire is burned; and therefore he remembers that this im- 
prudent A implies this painful B. As his experience grows 
the array of similar implications extends, and at a certain 
moment he finds, further, that B implies C. By a basic law 
of economy of mental effort, he eliminates B, and realizes 
that A implies C. 

From this point of view any train of thought may be re- 
garded as syllogistic, even if not rigorously so. The main 
difference between thought in the animal and in man would 
seem to be that among the animals the only symbols which 
can be used are those afforded accidentally by external 
stimuli, whereas man supplies his own symbols at will. 
Through this symbolizing power man has been led to various 
syllogistic chains of fundamental importance for the compre- 
hension of what goes on about him. It is the mathematician 
who has discovered, analyzed, classified the corresponding 
abstractions for their own sake. 

Thus, where the ancient mind was confronted with a world 
of concrete happenings and things, the modern mind is faced 
by their manifold abstract representatives to such an extent 
that the happenings and things themselves begin almost to 
seem of minor importance. Perhaps, then, the principal philo- 
sophical difficulty of our modern world is that we find our- 
selves adrift in a cold, buff eting sea of impersonal abstractions. 

Now when we survey the varied fields of scientific know- 
ledge we are led almost inevitably to divide knowledge into 
five categories or ' levels/ characterized respectively as mathe- 
matical, physical, biological, psychological, and social. 1 Here 
it is not the number of divisions which is to be regarded as 
especially significant, for there are intermediate domains. 
The important general truths involved are the following: 
(i) Each level is a natural one in the sense that it possesses its 
own especial fundamental intuitive language which is largely 

1 For the points of view here expressed see the concluding chapter 
of my book, The Origin, Nature and Influence of Relativity, New 
York, 1925, as well as an article in the Century Magazine for 1929. 
The classification of the levels given below and the principles I-V 
are quoted directly from my book. 


if not completely independent of that used in the other levels. 
(2) Every specific fact may be analyzed from any one of these 
levels taken as fundamental. For example, a child tosses a 
ball to another. The mathematician thinks of a sphere in 
space and time; the physicist, of a material body moving 
under the action of certain forces; the biologist perceives a 
biological significance in the act of play; the psychologist is 
interested only in the psychic accompaniment of the act; and 
the sociologist sees an instance of an important kind of social 
interaction. (3) According as we take one or the other of these 
levels as the most fundamental or ' real/ we are led to a corre- 
sponding systematic philosophic point of view. 

These levels, together with the corresponding systems of 
philosophy and fundamental terms, may be catalogued as 
follows : 

Mathematical, Absolute Realism : 

Class, Relation, Inference, Abstraction. 
Physical, Materialism : 

Space-Time, Matter, Electricity, Uniformity. 
Biological, Detailed Naturalism : 

Organism, Stimulus, Function, Evolution. 
Psychological, Positivism : 

Sensation, Memory, Will, Idea. 
Social, Ethical Idealism : 

Personality, Freedom, Value, Ideal. 

It may also be remarked that these levels form a kind of 
hierarchy in which the earlier levels are objective in the sense 
that they involve no explicit reference to personality, while 
the later levels are subjective, since they involve necessary 
reference to personality. The whole range involved may be 
termed the ' nature-mind spectrum of knowledge/ 

It seems to be probable that those who take a particular 
one of these levels as the most real are merely those who 
insist on starting in their thought from this particular level; 
for instance, I, as a mathematician, would naturally consider 
physical, biological, psychological, and social knowledge in 
so far as it is embodied in abstract form. If this is indeed 


the case, the only rational point of view is to regard all of 
these levels as having co-ordinate reality. 

The acceptance of this conclusion is of fundamental philo- 
sophic importance; in particular we are led by it not to be 
overwhelmed by the merely physical aspect of the vast uni- 
verse around us, and yet we are willing to grant that the 
physical world is so real that no set of mere abstractions can 
take complete account of it. 

Now if the general diagnosis of our present philosophic 
difficulty made above is correct namely, that we are con- 
fused by a large array of unco-ordinated scientific theories 
it is especially desirable that we understand their nature and 
function in the domain of knowledge. With this in mind let 
us proceed to observe certain general facts. 

I. Abstractions originate in the domain of the intuitively 

This reminds us that abstractions are natural and inevitable 
in their beginnings, however elaborate their final form may 
be. Language itself is a vast loose abstract structure, which 
develops along with thought. Consequently the earliest and 
least sophisticated notions of the human mind mark the be- 
ginnings of genuine permanent abstract structures, however 
incomplete and erroneous they may seem to be later on. In 
any case, such notions may be regarded as important prag- 
matic attempts to ascertain the inner nature of the world by 
means of certain hypotheses which are more or less true. This 
leads us at once to the second general principle. 

II. Every abstraction is to be applied in its appropriate 
domain of validity. 

It has been the hope of many to find some final dogma. 
This tendency has been exemplified, for instance, by those 
who ' believed ' in geometrical space in the sense of Euclid. 
But such persons forgot that the very process of measurement 
is so inaccurate that the geometric laws of Euclid can never 
be given a precise physical meaning; they also forgot that it 
was very unlikely from a philosophic point of view that 


certain geometric aspects of the physical universe were abso- 
lutely independent of all other aspects. Today we prefer to 
grant an independent reality to space-time rather than to 
space or time. But we hesitate to regard our new point of view 
as an ultimate one. 

Thus, more than ever before, we are inclined to look upon 
all abstractions as provisional and partial as more or less 
extensive nets for holding a certain aspect of the truth. The 
same thought can be expressed in the form that all abstrac- 
tions represent only a part the truth, with limited sharpness 
of focus. 

Accordingly all questions concerned with the possibility of 
unlimited application of an abstraction should be abandoned 
as meaningless. For instance, is the world deterministic or 
not? Obviously one indeterministic happening in every aeon 
of time is all that is required to make it indeterministic; 
furthermore, any series of happenings can be rationalized 
into deterministic form. Hence our query seems to be mean- 

III. As more complete abstractions are made, they may be 

expected to include their predecessors. 

In fact, since a more complete abstraction explains a certain 
group of facts and other new ones besides, it must be possible 
to show why the earlier theory is true to the extent observed. 
From this point of view any successful abstraction represents 
a definite step in advance. 

IV. The undefined elements, relations, and postulates of a 

particular abstraction are to a large extent arbitrary. 

An abstraction is merely a means of traversing systematic- 
ally a certain structure of thought. Theoretically we can start 
where we will, although our actual choice of a starting-point 
may be governed by considerations of convenience; thus, in 
geometry we may begin with points, or with lines, or with 
convex regions as the undefined elements. No one abstract 
basis can be regarded as more fundamental than another, 
although it may be more convenient. 


V. The usefulness of an abstraction is relative to its inherent 
simplicity of structure and its agreement with the 

Just because our minds are limited it is fundamentally 
necessary for us to employ the simplest abstractions which 
suffice to co-ordinate the facts before us. 

This conclusion does not mean that a simple abstraction 
without present application is to be regarded as without value. 
All abstractions are significant if they possess beauty; and the 
experience of the race shows that such abstractions are almost 
certain sooner or later to prove useful. 

With these general reflections concerning the field of 
knowledge, and more especially its abstract side, let us turn 
to the affirmations toward which they seem to point, particu- 
larly at what we have termed the ' social level/ 

In accordance with the first of the five general principles, 
we are bound to give fundamental weight to all genuine in- 
tuitions, no matter on what level they appear. They form the 
basic material from which we take our abstract start, whether 
the level be mathematical, physical, biological, psycho- 
logical, or social. In particular, ethical and religious intuitions 
are the fundamental material from which we start at the 
social level. These cannot be thrown aside, whether we will 
or no; and if we are wise we will give them the consideration 
which they call for. 

The second principle leads us away from all dogma, except 
as a means of enabling us to grasp a certain partial aspect of 
the truth. Here by truth is not meant the narrow, literal 
truth, but rather pragmatic truth. For example, the Christian 
religion has contained forms of dogmatic belief which in 
their literal interpretation are now generally held not to be 
true. But in its basic affirmation of the deep unity of all 
personality and the transcendent power of love and good-will 
it has emphasized a truth of the first order of importance. 
Thus the pragmatic truth of Christianity (and of other re- 
ligions) has been revealed by a positive, beneficial effect upon 


The forms by which this truth may be com- 
municated function as devices which work, although no doubt 
it is often for a reason quite different from that which we 
think. In fact, it is often the case that our vocabulary of ex- 
pression is so limited that we can only begin to grasp the 
essential truth in a realistic manner by means of forms which 
are incomplete and inaccurate. When we are thus forced to 
employ the imperfect means at our disposal, we should not 
hesitate in doing so. At the same time we ought not to cease 
our strivings towards a better understanding, since, according 
to the third principle, we can legitimately hope to succeed in 
our efforts. 

The fourth principle teaches tolerance towards all forms of 
belief, since abstractions with different undefined elements 
and relations are often substantially equivalent. In general 
two theories are to be regarded as essentially equivalent 
when they lead to the same pragmatic conclusions. 

Finally, in accordance with the last principle, we are led to 
estimate a social or religious code as a help towards a distant 
goal rather than as a final formulation, and as valid in an im- 
portant sense only when it contains much of the truth in 
relatively simple form. 

If the above general division of the field of knowledge is 
correct, religious truth falls at the social level. Thus God may 
be defined as the totality of personality, or rather as its highest 
form, which transcends our understanding. Since all person- 
ality must be definitely embodied and developing, if it is to 
be personality at all, God must possess a Personality as defi- 
nite, for instance, as the particular physical universe around 
us. Moreover, since the totality of personality is unitary, all 
of its parts are definite and eternal, being constituents of a 
developing whole. Thus it is impossible, for me at least, not 
to conceive of life as ultimately triumphant over death. 

Moreover, I am encouraged in this belief because I know 
how inconceivable is the range of abstract possibilities which 
may turn out to be actual. As Hilbert has recently declared : 
"We ought to know, we shall know." In other words, no 
logically conceivable task is beyond the ultimate power of 


the human mind. I shall mention one possibility in order 
to illustrate my idea. Why may it not happen that a 
way will be found at last by which to unite the past with 
the present, so that personality can develop along the 
whole line of time? This would necessitate a new kind of 
time, related to ordinary real time much as the ' imaginary 
numbers ' so fundamental for the mathematician are related 
to ordinary real numbers. 

Thus my own tendency is toward a social and spiritual 
point of view which contains a considerable amount of faith, 
but no specific dogma. This faith appears to me to be justified 
in the same way as my faith at the other levels, in particular, 
at the mathematical level, and to be an equally inevitable 
result of my individual experience. 

Perhaps, then, the primary service of modern mathematics 
is that it alone enables us to understand the vast abstract 
permanences which underlie the flux of things, without re- 
quiring us to regard its self-consistent abstractions as more 
than specific, limited instruments of thought. 



Professor of Philosophy in the University of Naples 

F AHE traditional manner of considering rationality 
I envisaged it as a system of conceptual entities, of un- 

JL changing essences and laws, in an order established 
ab xterno. Rationality thus considered could not be recon- 
ciled with the creative activity of the spirit, and conflicted 
with the reality of history, which implies the possibility of 
the generation of new orders of existence. Hence abstract 
rationalism has always declared life in time to be an illusory 
appearance, and has sought in vain to resolve the antinomy 
of freedom and predestination. This mistaken manner of 
considering rationality was shared by the old empiricism, 
which was no less abstract than the rationalism it corn- 
batted, and which in its turn hypostasized an immutable 
order of laws in eternal nature, communicated to our con- 
sciousness through external impressions. 

The first attempt to break through the iron circle of pre- 
determined rationality is to be found in Kant, who con- 
siders the forms of intuition and the categories as modes of 
the activity of the mind. But at bottom he does not succeed 
in freeing himself from pre-formist prejudice; for him the a 
priori of sense and intellect still presents itself as a stereo- 
typed form, which the mind discovers in itself by regressive 
analysis, but which it does not itself produce. We cannot 
help thinking in the eternal forms that Kant thought he 
could establish in his table of categories. 

Hegel in his dialectic assumed the task of moulding 
rationality to the movement of history. Yet even he did not 
really succeed in introducing dynamism into rationality, 



since the concepts of his logic, though set one after the other 
and linked by an intrinsic necessity causing us to pass per- 
petually from one to the other, are still the old abstractions 
of hypostasized intellectualism, enclosed in a circle in which 
our thought must go round and round for ever. Now this 
continuous circular motion is a simulation of process, but no 
real and historical development. Where the stages of 
thought are predetermined, there is no true process. There 
is no freedom where the mind is constrained by necessity to 
traverse always the same concepts, the same determinations 
of reality, unchanging and unchangeable. 

The traditional manner of considering rationality, as a 
system of closed concepts and relations, failed to satisfy our 
indestructible need to attribute a meaning for our life as it 
evolves in time. 

If the whole of reality is already complete and perfect in 
an eternal order, there remains nothing more to do in the 
world. All the strivings of our busy wills must be in vain. 
Hence a profound discord between logic and life. But as 
we shall see, this discord, that became acute towards the 
end of the last century, has been gradually attenuated by 
the new developments of contemporary logic; it is possible 
to envisage rationality in a truly dynamic manner, so as to 
make it correspond to the most concrete exigencies of life 
and history. 

Hegelian dialectic answered a real need: to provide us 
with the concrete universal. The old logic attained to unity 
by obliterating differences. Rising step by step to concepts 
of ever wider generality till it reached the idea of simple 
Being, it progressively diminished their content till this was 
wholly eliminated. Thus all the wealth of concrete deter- 
minations was lost, and unity, thus attained, unified noth- 
ing, for it fell outside multiplicity, which it did not syn- 
thesise, but on the contrary excluded. The concrete uni- 
versal, on the other hand, which Hegelian dialectic seeks to 


construct in its process, is a synthesis in which all the deter- 
minations of reality are preserved the living organism o 
thought. The old logic, from considering the concept in its 
identity and immutability as something real, was led to ex- 
clude change. It was Hegel's merit to have discovered that 
every contradiction is relative to a certain unilateral outlook 
on reality, and that if we raise ourselves to a higher and 
more comprehensive standpoint our thought can embrace 
and reconcile in a wider outlook two fragmentary views that 
seemed to exclude each other if considered from two uni- 
lateral viewpoints. 

It is evident that the Hegelian dialectic works outside 
time in a closed cycle, turning and returning eternally upon 
itself. In fact, it contains no true process, for the whole 
system of categories is given from the beginning. And it is 
not comprehensible how Absolute Thought, that in itself 
contains the full concreteness of all determinations, should 
have to return and retraverse the unilateral and abstract con- 
cepts. In conclusion, in the Mind of God, in the Absolute, 
there is no sense in speaking of a dialectical process. Such a 
process has meaning only from the viewpoint of the finite 
mind, which does not comprehend in itself the whole fulness 
of reality, and is therefore constrained to unilateral and 
abstract views. 

This manner of envisaging dialectic, that is, as the succes- 
sive approximation of human thought to the system of the 
Absolute, overcoming the abstractions and contradictions 
of our intellect step by step, was maintained by the Italian 
philosopher Vincenzo Gioberti towards the middle of the 
nineteenth century. 1 And the British neo-Hegelians, especi- 
ally Bradley and M'Taggart, towards the end of the nine- 
teenth century, conceived of dialectic in the same manner. 
This perfectly coherent system is the criterion of truth, im- 
manent in the human consciousness, which, being bounded 
and fragmentary, lays hold of certain groups of relations 
detached from others, and only under certain one-sided 
aspects. Our consciousness never, therefore, gives us full 

1 In the last phase of his thought, when he drew near to Hegel. 



reality, and is constrained to reconstruct by means of abstract 
concepts the synthetic unity that for ever eludes it. Judg- 
ment, says Bradley, is always inadequate; by judgment we 
qualify what is given us in experience, a certain subject, a 
certain that, by a predicate, a what. But like all other rela- 
tions, this gives rise to contradictions. Qualities cannot exist 
save in so far as they are distinct, that is, they imply at least 
the relation of diversity. But relation in its turn has no sense 
save in as much as it holds between certain terms, of which 
it therefore presupposes the existence. Moreover, if the rela- 
tion is thought of as something distinct from the terms, 
there arises the problem of understanding its reference to 
these terms. This involves the understanding of an infinite 
series of relations and the series will never be closed, for our 
finite thought can never embrace the totality of relations. 
Science, which seeks to understand reality by relations of 
space, time, cause, substance, etc., goes round and round, 
therefore, in a world of contradictory appearances. 

While Hegel accepted the categories and concepts of the 
science of his time without demur, and, while proclaiming 
them abstract, transported them into the eternal cycle of his 
dialectic as moments through which thought must always 
pass, the new British Idealists, while taking their stand in 
opposition to empiricism and evolutionism, recognise the 
relative character of scientific concepts. They are working 
ideas, according to Bradley, who in this agrees with his Prag- 
matist adversaries. But, though partial aspects, they do not 
fall wholly outside reality. The whole and completely har- 
monious system of the Absolute must comprehend them all, 
allotting them their rightful place, integrating and correct- 
ing their abstraction. Even an appearance is, and hence must 
somehow belong to reality. There is no error that does not 
contain a certain measure of truth. The appearance that, 
in order to be converted into an absolute, requires less addi- 
tion and rearrangement possesses a greater measure of truth. 

And here it is that the inadequacy of Bradley' s logic re- 
veals itself. Extremely brilliant and penetrating when em- 
ployed in negative criticism, it is unable to give us any 


positive criterion whatever of truth. How, indeed, can we 
measure the degrees of truth? 

Once reality is postulated as an already given whole in 
a total and eternal synthesis, British neo-Hegelianism is 
unable to assign meaning to our life in time, to the world of 
our human experience as it evolves in history. One fails to 
understand why what is already made should need to re- 
make itself. Thus dialectic ends by owning its own inade- 
quacy and by appealing to the irrational. This is plain in 
that immediate intuition of which Bradley speaks, and in 
the mystical love that is the final recourse of M'Taggart. 

For M'Taggart, indeed, dialectic has only a purely sub- 
jective value. It is not for him as for Hegel the very process 
of Absolute Reality, but only the mode in which the finite 
consciousness attains thereto, by progressively freeing itself 
from error. 

One might ask M'Taggart what remains for us to do, and 
what gives rise to time, to which we cannot help assigning 
a certain form of existence. If it is outside the Absolute, 
how can one envisage its coexistence with the Absolute? To 
call it an illusion does not dispense the philosopher from the 
task of explaining this illusion. The deeply human problem 
of bestowing a meaning upon our life in time in M'Taggart' s 
static conception remains unsolved. To solve it we should 
have to bring the Absolute forth from its immobility, to give 
it the motion and warmth of life by recognition of the reality 
of change. And such has been the endeavour of Bosanquet 
and Royce. 

For Bosanquet dialectic is not purely subjective and illu- 
sory, but reproduces the inward dynamism of reality. It is 
not the simple contradiction between abstract concepts, but 
the concrete opposition between the various parts of the 
world of our living experience. Bosanquet, while reducing 
everything to thought, uses this word to signify the whole 
of our spiritual life enlightened by the light of consciousness, 
thus including feeling and will. 

The very fulness of dynamic life, which includes in itself 
all the contrasts of the world, all the infinity of time over- 


come in its eternal present, is to be found in the Divine Con- 
sciousness as conceived by Royce. It is the eternal signifi- 
cance of all our ideas; that is to say, it is the ultimate end 
they seek to realise, since our every thought is at the same 
time an act of will. In it alone is there an end of all am- 
biguity and of that indetermination that is present in all 
knowledge, in all human judgments. But it contains also 
imperfect truths, partial satisfactions, errors, as unilateral 
views in the total vision of the Absolute, in which they find 
their complement and correction. It would seem that thus 
Royce preserves the life of time, transferring it with all its 
joys and sorrows, with all its falls and all its victories, into 
the very life of God. But in reality, if everything is already 
done, the prospect of the future is only a fallacious sem- 
blance, due to our own fragmentary outlook. We delude 
ourselves that there remains still something to do, when all 
is already done. It avails nothing to appeal to the new 
mathematical theories of Dedekind and Cantor, for the in- 
finite, if it is truly infinite, must be thought of as inexhaust- 
ible. Instead, if all the terms of the series of time are con- 
sidered as already given, if their synthesis is put forward as 
completed, it is already exhausted. History, which we be- 
lieve we can still construct, is already constructed down to 
the smallest detail. 

For the historical process to be truly real, the spirit must 
have the possibility before it of ever fresh creations. Every 
fixed limit confining its activities must be removed. To this 
task Italian neo-Hegelianism set itself. According to Gentile, 
Hegel's mistake lies in having placed the Idea and its dia- 
lectical development in itself and in nature before placing it 
in consciousness, forgetting the Kantian discovery of the 
categories as an activity of thought and the necessary pre- 
supposition to any concept. Dialectic must not be applied to 
objects thought, which in themselves are abstractions, and 
for which the old logic of identity holds good, but to the 
very activity of thinking which in every one of its moments 
is full concreteness. Beyond or before this concrete act noth- 
ing exists. The study of objects must be left to science; 


philosophy is reflection on the concrete activity of thought 
and cannot avail itself of the method of abstract logic, since 
the spirit is not something that can be contemplated as a 
fixed object with immutable properties. One cannot say its 
activity is, but that it becomes. Its reality lies in its eternal 
self-making. Thus it cannot be understood otherwise than 
dialectically, for its life realises itself precisely in the con- 
tinuous transition from being to not-being, in which it re- 
news itself in a process of inexhaustible creation that is at 
once its own history and the history of the world. But this 
concrete logic cannot realise itself save in as much as 
thought, in its necessity of self-objectivation passes eternally 
through the old logic of identity, which is always being re- 
born always to be overcome. To reflect on itself, the spirit 
must issue forth from its immediacy and obj activate itself; 
but in this obj activation it seizes only the past moment, that 
which no longer is. It apprehends itself as nature, not as 
spiritual activity. The life of thought, in its concrete actu- 
ality, is to be found in this eternal transition from subjective 
immediacy of feeling, which in art gives its own colour to 
everything, to the objective moment, which is religion, in 
which the subject denies itself in order to oppose to it- 
self an infinite object. Thus Gentile, returning to Fichte, 
concentrates dialectic in the act of self-consciousness, in that 
which for Hegel was only the final triad of the process. And 
in these three moments Gentile vainly endeavours to con- 
fine all the functions of the spirit. Thus the negative 
moment, the anti-thesis, the not-being, gathers into its in- 
determination our past, all other empirical individuals, 
nature, law, God, error, evil; and when the philosopher says 
that these are born from the abstract objectivation of 
thought, he does not give any reason for their diversity. Nor 
does it avail to say that no two moments are identical, and 
that therefore the thinking activity in its self-objectivation 
engenders infinite distinctions, for in that way all distinc- 
tions would be set on the same level. God, for instance, 
would be distinguished from a human individual as one 
empirical person from another, and one fails to understand 


why God should be worshipped and not this or that person. 
Moreover, only by an artificial and arbitrary definition of 
art and religion, making them present themselves as oppo- 
sites, is the dialectical passage from one to the other rendered 

A greater respect for concrete distinctions is to be found 
in Croce's Philosophy of the Spirit, 1 in which attempts a 
more radical reform of the Hegelian dialectic. In accordance 
with reason he abandons the attempt to create artificial oppo- 
sitions where they do not exist. Oppositions, according to 
Croce, exist only in the ambit of each function. Thus in art 
we find the antithesis of beautiful and ugly. For these con- 
traries the dialectical principle holds good that reality lies 
in the synthesis of the two, that is, the positive is realised 
not by the exclusion of the negative, but by including it in 
its higher concreteness. But in the relation between the 
various forms of the activity of the spirit there is distinction, 
not opposition. Art, for example, as intuition of the moment 
of individual life, is the first grade of knowledge, from which 
the spirit rises to the higher grade of philosophy, the thought 
of the universal in its concreteness, in which intuitions are 
not eliminated but comprehended. The first grade exists as 
a moment distinct, not separate, from the second, which 
instead implies the first, for there is no thought without in- 
tuition. In the same way the moral will, which is the higher 
grade of the practical activity, implies the lower, that of 
utilitarian value, for it is not possible to will universal good 
without at the same time willing a particular good. But the 
economic will, which aims at the useful, subsists as a distinct 
and independent grade from the moral will. And a relation 
of distinction must be posited also between the theoretical 
and practical activities, for action presupposes thought, but 
thought can subsist -as a distinct moment of the life of the 
spirit. This ideal succession of moments (not to be confused 
with a real and historical succession), is what Croce calls the 
dialectic of distincts. These have concrete subsistence in 

1 Needless to say, here as elsewhere, I am following a logical and 
not a chronological order. 


consciousness, for they can be distinguished in the unity of 
the spirit, which comprehends them all in its every throb of 
life. The opposites, on the other hand, are abstractions that 
have no reality distinguishable of one from the other. 

There is no a priori justification for the ideal order of 
moments, and less still for the eternal circle conducting the 
spirit eternally from one to the other. As a matter of fact 
these determinations of spiritual functions are not dialectic- 
ally constructed, but drawn from experience. The schema 
of distinction, like that of opposition, does nothing but 
distort them, defining them a priori, in such a way as to 
enable them to be ranged in that given cycle of categories. 
And the speculative method, without rule or check, making 
of sole subjective thought a norm unto itself, can construct 
its table of spiritual categories at will. And this varies ac- 
cording to the philosopher. Thus theory and practice are 
identical for Gentile, while they are diverse for Croce. 

It is now time to shatter these last constructions in which 
rationalism, convinced of its impotency dialectically to con- 
struct the categories of the natural world, would seek to con- 
fine the forms of the spirit. There is no circle in which our 
conscious life is condemned to go round and round forever. 
The claim to characterise these forms of all eternity is ille- 
gitimate. Thus the categories of the world of nature, like 
those of conscious life, are not fixed patterns or rhythms 
through which experience must pass eternally, but variable 
constructions in which empirical activities, while losing 
nothing of their concreteness, find co-ordination through the 
integration and enrichment of their life. Mutable forms, in 
their concrete historical development, in which they assume 
individual aspects that are always unpredictable, they peren- 
nially shatter the old equilibriums and give rise to fresh 
syntheses, in which both they themselves and their dynamic 
relations are transfigured. Hence we set a false problem 
when we would settle once for all what is art and its relation 
to religion or to philosophy, or would determine infallibly 
the nature of Right in its relation to moral life. History 
knows nothing of fixed paths on which it must move 


eternally in courses and recourses; it builds its own road, 
testing and retesting, in order to compose its living energies 
in ever higher forms. 

To a superficial gaze Pragmatism and Intuitionism are the 
antithesis of neo-Hegelianism, and the philosophers of the 
two hostile tendencies have waged long warfare. But, at 
bottom, there is a common aspiration: that of equating 
logic to life, of rendering it concrete, thus overcoming the 
old abstract rationalism. This tendency is the hall-mark of 
the nineteenth century, which was historicist and evolu- 
tionist, in contrast to the eighteenth, with its idols of a 
motionless Nature and a motionless Reason. The theory 
of evolution, in fact, gave birth to Critical Empiricism, 
which brings logic back within the development of life, con- 
sidering it as an organ of biological adaptation. The myth 
of the immutability of logical forms has been overthrown, 
together with that of the immutability of organic species. 
Not only that, but while the transformation of living species 
remains an unverifiable hypothesis, the evolution of mathe- 
matical and physical concepts, of the principles and cate- 
gories with which scientific theories are built up, is an un- 
deniable fact to be observed in the second half of the nine- 
teenth century. The construction of non-Euclidean geo- 
metries, the crisis of mechanism resulting from the discovery 
of the second principle of thermo-dynamics, the rise of the 
science of energetics, the new studies on the transformation 
of chemical elements, all lead scientists to put away their 
traditional prejudice in favour of a single type of theory, an 
immutable logical structure, through which the complex of 
phenomena must necessarily pass in order to be known. In- 
numerable theories, starting from different primary concepts 
and different primary relations, are equally possible. And 
among them there may be free choice, so long as their con- 
sequences are borne out by the facts. The old categories of 
cause, substance, action, no longer appear as indispensable 
logical forms if phenomena are to be intelligible. In fact, 


following the lines traced by Rankine and Mach, there is a 
readiness to replace them by the concept of a mathematical 
function between certain variable magnitudes. 

A profound revolution in method has thus taken place, 
seeming at first a discrediting of science, a crisis of human 
reason, and liable to encourage mystical castles in the air 
and emotional vapours. But what has really happened is 
that it is the old, dead Goddess of Reason of the eighteenth 
century who has tumbled from her altar, to make room for 
a living Reason which does not mirror immutable reality 
from without, but places itself in the very heart of reality, 
and actively contributes to its development. 

As when we were dealing with neo-Hegelianism, in treat- 
ing of Critical Empiricism, Pragmatism and Intuitionism, 
we shall avoid the barren standpoint of negative criticism, 
preferring to emphasise their positive contribution to this 
idea of a new logic moulded to the movement of life. When 
Avenarius and Mach tell us that concepts are organs for a 
better adaptation of the organism to the world of its experi- 
ence, and that their purpose is to master it in the simplest 
and most economical manner, the concept does not lose but 
gains in value. 

Assuredly Critical Empiricism has its defective side. As 
when it claims to explain the tendency to unity by the need 
for mental economy, taking into consideration only the sim- 
plicity of the schema, which is the sign for the concept, and 
leaving out of account the highly complicated dynamism of 
mental operations in which its true reality lies, a complexity 
that increases more and more with the ascent to more 
general concepts. 

The Pragmatism of James, Schiller and Dewey un- 
doubtedly reaches a higher level than Critical Empiricism, 
in as much as it rejects the atomic resolution of the Ego into 
a mere aggregate of elements, and insists on the continuity 
of the stream of experience, in which data and relations can 
be isolated only by abstraction. The individual activity of 
the subject in the construction of things and concepts is 
vigorously asserted. Critical Empiricism continued to con- 


sider the concept as a mechanical result, as the precipitate 
of a series of sensations, and, while assigning it an active 
function, reduced it to a complicated mechanism of reflex 
actions such as the word or definition of the concept might 
suggest. It reduced the mental act to a kind of representa- 
tion of actual physical movement. In Critical Empiricism 
the materialist and determinist outlook on life and its adap- 
tation had yet to be overcome. Pragmatism, on the other 
hand, attributes a real efficacy in world-construction to the 
human will. And here precisely lies its undeniable merit, as 
contrasted not only with the old rationalism, which con- 
ceived of reality and truth as something ready-made, inde- 
pendent of our working, but also with British neo-Hegel- 
ianism, which, as we have seen, posited over against human 
conscious and prior to it, an Eternal Consciousness in which 
the whole system of reality was contained and exhausted. 

Having denied that a total and divine system, of which 
we can humanly form no idea, could serve as unit of 
measurement of degrees of truth, Pragmatism felt the need 
of a criterion that would be effectively applicable, and be- 
lieved that such a criterion was provided by social utility, 
whether of concepts, principles, or logical structures. The 
convenience, suitability, of which James, Schiller and Dewey 
speak, does not mean the mere satisfaction of the individual, 
but also that which renders social agreement possible. And 
there are certain conventions, such as those of logical prin- 
ciples, which must be respected if men are to understand 
each other. But in this wider sense utility becomes a very 
vague expression and can be made to cover almost anything. 
And here precisely is the weak point of Pragmatism: its 
criterion of truth remains indefinite. We must explain what 
we mean by social utility. Is it maybe the greatest happiness 
of the greatest number of individuals? But by now, since 
John Stuart Mill, the qualitative distinction of forms of hap- 
piness and the need to place them in hierarchical order has 
become a commonplace. We must appeal to an end, to a 
higher norm of valuation. And if the useful is taken as that 
which corresponds to the ends of society, these ends still re- 


main to be determined. What is the ideal towards which the 
life of experience, in which we all participate, is tending? 
Schiller speaks of a final harmonious perfection of activity. 
Dewey describes the evolving movement of experience as the 
rise of conflicts within it, leading to the relative distinction 
of data and ideas that serve to rearrange, reorganise and 
harmonise it. But it is just the meaning of the word agree- 
ment, of the word harmony, that the Pragmatists fail to ex- 
plain. They over-emphasise the action of the subjective 

But if we turn aside from these paradoxical exaggerations, 
which are the ephemeral part to which, from controversial 
motives, in reaction to chill intellectualism, too much em- 
phasis has been given, and if we consider more intrinsically 
the meaning of the formulas convenience, utility, power of 
action and of foresight, we see that at bottom they signify 
the concrete agreement of our human wills in a world of 
experience unified by our concepts so as to make it converge 
towards the realisation of our ends. Here, then, is the same 
aspiration towards the concrete universal that we emphasised 
in neo-Hegelianism. They place the criterion of truth not in 
that perfectly harmonious system, immanent in our spirit as 
an immutable model, but in the process of action by which 
it is realised, and which, by its success in the world of our 
experience, affords us proof of the ever vaster agreements 
we are gradually achieving by our logical constructions. 

The same tendency to reabsorb logic into the movement 
of life is to be found in the Philosophy of Action and the 
Intuitionism of France. Assuredly, if scientific knowledge 
is made to consist in reduction to identity, it is easy to show 
with Boutroux, Milhaud and Meyerson that concrete reality, 
in the wealth of its changing aspects, falls outside our for- 
mulas. And it is this abstract mode of understanding the 
concept, as a rigid schema always identical to itself, that 
Bergson rightly judges to be incapable of giving us under- 
standing of the process of continual renewal, of inexhaust- 
ible creation, that goes on in our living experience. But there 
is another manner in which the intelligence may be con- 


sidered, and that is in the concrete spiritual process of its 
active production not the ready-made concept, not the 
already petrified lava, but its incandescent flow before it 
cools and becomes stone. 

Le Roy insists repeatedly on the fact that intuition is not 
opposed to intelligence, but reintegrates the intelligence in 
itself by seizing it in its living dynamism. It is reason, not 
immutable and enclosed in an eternal codex of laws, but 
evolving in an inexhaustible process and able to create new 
rules and new categories reason, which operates, and which 
in action experiences its truth. 

Intuition thus approaches Pragmatism. But Le Roy re- 
fuses to allow the intervention of any extraneous or alien 
motive, any consideration of convenience or of utility of a 
lower order, in the determination of truth. Fruitf ulness must 
be homogeneous with the order of thought in which the 
theory evolves. The true idea is the idea that bears fruit, 
but in the domain of knowledge itself, not in that of in- 
dustry or even of feeling or moral comfort. It is the idea con- 
ceived as a scheme, as a plan of battle, and which fulfils its 
promise, triumphing precisely in the action it suggested. 

There still remains much that is indeterminate in this 
way of envisaging truth. Fruitfulness in the realm of know- 
ing can only signify the capacity to make us discover other 
truths, and thus to enrich our knowledge. It presupposes 
that we have already determined the sense of just that word, 
truth. And since we must rule out other ends we must de- 
termine the end of cognition, since the idea cannot under- 
take to realise another plan diverse from its special cognitive 
function. But in what does this cognitive function consist? 
Here is the essential problem, and Le Roy leaves it unsolved. 
But he is to be noted for his brilliant endeavour to introduce 
reason into the very movement of life, directing intuitionism 
towards that concrete and dynamic rationalism to which, as 
we have seen, the development of contemporary logic tends. 

The dialectic of the moral life, according to Blondel, 
should carry us instead beyond experience. The principle of 
contradiction does not lie in facts, which can neither pro- 


duce nor suggest it. Opposites are such in virtue of their 
agreement or disagreement with the trend of our tendencies. 
The notion of the contradictory comes to us from the feeling 
of the irrevocability of what we have willed. The real and 
original , meaning of the principle of contradiction is that of 
establishing that what might have been, and what in virtue 
of our action might have become part of what we are, is 
ruled out for ever, and yet does not cease to enable us to 
think distinctly what has been chosen and done, nourishing 
the effort of knowledge and execution, and giving moral 
determination to both the realised act and the agent. 
Whereas abstract negation destroys the concept denied so 
that no trace remains, the privation of anything leaves the 
scar of the act that retrenched it in the potentiality that 
could have realised it. Not only what we do but what we 
renounce contributes to our making. Repressed tendencies 
remain to point the meaning, to determine the cost, to 
nourish the life of the tendencies that triumph. Our option 
once made neither of two contraries survives alone; a new 
reality is created. A realised idea is no longer the same as it 
was before it was chosen from among others and opposed to 
others. The sum of human activity thus does not develop 
along the line marked by the simple, clear idea that, maybe, 
we think is our sole guide. The logic of life unfolds along 
the diagonal of the parallelogram of all concurrent and co- 
operative forces. In this logic truth is the agreement of 
thought and life with itself, not in the purely formal sense, 
but in the concrete signification of a complete equation of 
what we do, of our realised will, with what is implicit in our 
deeper will. And this deeper will does not realise itself all 
at once, but achieves itself little by little through the resist- 
ances offered by sensible nature, by the bodily organism, by 
human society, by the whole universe. Blondel's dialectic of 
action works itself out in showing how the deeper will 
realises itself through the co-operation of contrary forces, 
urged on from stage to stage by the discrepancy between 
what it has realised and the infinite Being it aspires to 
possess, till it reaches the final choice between the incomplete 


satisfaction that is all that can be obtained in this wor 
possession of Absolute Reality, in which alone si 
deeper will be satisfied and our being find full realise 
vital option that expresses itself precisely in the prir 
contradiction : either to be, with God, or not to be, 
finite world. 

Whatever the value of Blondel's Philosophy of 
bears vigorous witness to what we consider the fu 
motive of the development of contemporary log 
the demand for a concrete rationality that shall r 
to the movement of life. 

The new theories of the deductive and inducti 
tend in the same direction, emphasising the crea 
of thought in all reasoning. The old school logi> 
reasoning consisted in the subordination of one 
another and wider one, is now cast aside. The 
contained in the premises, but is something new 
structed. Mathematical reasoning, says Goblot, 
passage from the general to the particular, but tl 
from one property to another and heterogeneous c 
from the equality of the sides of a triangle it deduc 
equality of the angles) or to a more general property 
from the theorem of the sum of the angles of a triangle we 
pass to that of the sum of the angles of a polygon). Poincare 
believes he has discovered the foundation of generalisation 
in mathematics in recurrent reasoning, in which it is proved 
that if a theorem is valid for i, for n-i, and for n, it is valid 
for all numbers a reasoning that has as basis a synthetic a 
priori judgment. It is to Goblot's credit to have insisted on 
the constructive character of mathematical knowledge a 
fact that already, at the beginning of the eighteenth century, 
the genius of Giambattista Vico had clearly intuited and ex- 

The old geometry frequently appealed to intuition. 
Recent developments in mathematics tend, on the contrary, 
to give geometry the form of an abstract, logically rigorous 


theory, in which all the concepts and all the propositions we 
employ are explicitly enunciated. Even the evolution of 
mechanics has induced scientists (such as Rankine, Mach, 
Ostwald, Duhem) to strip their theories of representative 
elements, and if other physicists like Faraday, Thomson, 
Lodge, Maxwell, Garbasso, have recourse to concrete 
mechanical models, they admit that these images may vary, 
and consider them equivalent if they represent the natural 
relations of phenomena equally well. Hence representative 
elements have come to appear, in their variability, as some- 
thing accidental in respect of the constant relations sym- 
bolised by such models. 

The result has been to reduce every physical or mathe- 
matical theory to an assembly of logical deductions drawn 
from a certain number of primary relations (postulates), 
which are asserted as subsisting between certain primary and 
indefinable concepts. The entities and the primary postu- 
lates may be chosen at will. Thus, instead of starting from 
the straight line and the plane in order then to define the 
sphere, Lobatschewsky in his non-Euclidean geometry de- 
fines the right angle and the plane by means of the sphere. 
The principles that serve as starting-points have not the char- 
acter of self-evidence they possessed for the old rationalism. 
There are, however, certain conditions which must be 
satisfied by the primary entities and primary propositions. 
Terms left undefined must be such that by their means every 
other term can be defined, and propositions left unproven 
such that from them all the other propositions may be 
obtained by the sole use of formal logic, without any appeal 
to intuition. Other necessary conditions are the independ- 
ence and mutual compatibility of the primary propositions. 
It must not be possible to deduce one from the other, and 
they must not imply any contradiction. 

Mathematics having thus assumed an abstract form 
through the elimination of any remnant of intuition, they 
have tended more and more to identify themselves with 
logic. Mathematical logic, or Logistic, has thus arisen, in 
which logical concepts and operations are symbolised by 


signs analogous to those of algebra, particularly through the 
work of Boole, Schroder, Pasch, Peano, Whitehead and 
Russell. All these logicians are agreed on the value to be 
assigned to mathematical theories. These, according to 
Pieri, a disciple of Peano, are hypothetical deductive systems, 
that is, they always take the form: "if the hypotheses 
posited at the beginning are true, these consequences neces- 
sarily follow." 

One of the basic conceptions that the new realism has 
taken from mathematical logic, and which forms, one might 
say, their main decisive weapon against the idealism of 
Bradley and Royce, is the doctrine of the exteriority of rela- 

Meinong, too, as against the intemperance of Psychologism 
and Critical Empiricism, has maintained the legitimacy of a 
Theory of Objects, that is, of a theory of rational essences, 
independently of any consideration of existence, and he has 
gone still further than Russell, for he admits even impossible 
objects, beyond the compass of our thought, such as the 
round square ! 

The selfr-subsistence of the immutable essences even before 
they are discovered by consciousness is a dogmatic assertion 
made by the new Realism, and one which, while it can in no 
wise be proved, gives rise to insuperable difficulties. How can 
it ever be possible to explain the varied grouping of these 
entities and these relations in such a way as to engender the 
phenomena of our human experience? According to the 
New Realists there is an entity red, an entity round, an 
entity consciousness. But how is the fact objectively pro- 
duced that at a certain moment I think of a red ball? It will 
be answered that the three entities come into relation. But 
this relation in its turn subsisted immutably from all 
eternity. How will it ever be possible objectively to deter- 
mine the fact that this relation subsists in this moment 
between these three entities and not between an infinite 
number of others? 

The hypothesis of the self-subsistence of the universals 
does not help us at all. So long as they remain in isolated 


self-subsistence they mean nothing to us; their function be- 
gins when they enter the world of our conscious experience. 
That the principle of causality, for instance, should be an 
eternal essence does not concern us at all. What we want to 
know is whether it is universally valid for our experience. 
You tell me that the principle of causality can enter into re- 
lation with other elements of our world. But who assures us 
that it will do so, who guarantees that it will always hold good 
in our world? In final analysis, if we remain in the pure do- 
main of the essences, we have before us infinite possibilities 
that may combine into infinite systems. Which of these 
theories may be true for our world only experiment can 
decide. Russell agrees in this, and he, too, recognises, there- 
fore, that some of the categories now used in scientific systems 
may be cast aside if others will serve the purpose better. But 
then what is the good of supposing them eternal in their 
essences? And who authorises Russell to project the logical 
constants that are the result of his personal analysis into the 
heaven of eternity? Other mathematical logicians consider 
other concepts and other elementary relations as the primitive 
ones. The analysis of the world of our experience may be made 
in an infinity of ways from an infinity of viewpoints. How 
can you claim to fix the results of analysis once and for all? 
Russell reduces philosophy to a repertory of abstract possi- 
bilities, and believes that thus he is widening the horizons of 
thought beyond what is actually experienced. But he sup- 
poses these abstract possibilities as already given from all 
eternity. And we hold that the true infinity, which does not 
limit thought, is one which, far from being exhaustible in a 
repertory of eternal essences, allows the human spirit the 
power to create new ideal orders, new categories unregistered 
in any inventory. 

We have seen how the recent developments of logical 
theories converge towards an idea of rationality correspond- 
ing dynamically to the life of history. But we noted at the 



same time a lack of any precise determination of that con- 
cept of concrete truth, and above all the lack of a criterion 
that would enable us to measure its degrees and liberate us 
from arbitrary dialectical constructions, subjective satisfac- 
tions of sentiment, or dogmatic acts of faith. This criterion, 
to my mind, should lie in experiment, which, at bottom, we 
all accept in the domain of science, and which should also 
enable us to find a common ground of agreement in that 
which concerns philosophic truth. 

The traditional theory that makes truth consist in a cor- 
respondence of human thought with things in themselves, 
and for which our ideas are simply reproductions of objects 
or objective essences, cannot be reconciled with the method 
of experiment. For an experiment is an action modifying 
reality more or less profoundly, whereas, according to the old 
criterion, we should mirror reality without contributing any- 
thing of our own. Thus experiment, as regards both its start- 
ing-point and its goal, is an active modification of reality. It 
does not reproduce an order of things and facts as existing 
in themselves, as naive realism depicts them to the imagina- 
tion of the vulgar, but produces always something new. Let 
us take one of the simplest experiments, that of the motion 
of the pendulum. The physicist takes a very fine thread, of 
which the weight is negligible as compared with that of the 
little ball attached to it, and causes it to oscillate in a vacuum 
so as to eliminate, as far as possible, the effects of friction. 
In other terms, he arranges the conditions of the phenom- 
enon, combining them in a suitable manner so as to make 
them approach a certain ideal type. And not only does he 
intervene thus actively with his thought at the start, con- 
structing a situation, which without his action would not 
have existed, but he intervenes also at the end, elaborating 
the result of his experiment. He does not limit himself to 
noting down the bare data of his various observations, but 
he adds them up and subjects them to calculations in order 
to obtain the most probable averages of the different numeri- 
cal values obtained by his measurements. He generalises 
them and brings them to the ideal synthetic perfection of the 


law of isochronism, to which experience may approximate, 
but which it never attains in any precise manner. All the 
principles of physics, all its laws, are ideal constructions of 
this nature. They are typical models, which do not merely 
sum up the facts experienced, as naive empiricism might 
suppose, but which are actively produced by our thought; 
our thought pursues on its own account and brings to an 
ideal limit of perfection the process which actual experiment 
can only approximately fulfil. 

We have chosen one of the simplest facts that comes 
closest to sense data in order to show that even here thought 
is operative, but it would have been far easier for us to 
emphasise the action of the physicist in more complex ex- 
periments, when, as with the phenomena of electricity, the 
bare data have no direct reference in themselves to that 
hypothetical energy. It is the scientist's mind that, by inter- 
preting them, sees magnetic fields, positive or negative poles, 
transmissions of currents, discharges of electrons, where the 
senses present us only with wires and pieces of metal, glass 
tubes, sparks, movements of pointers, registering apparatus, 
and so forth. We may therefore legitimately conclude that 
experiment is not the passive mirror of a supposed nature, as 
realism would have it, beyond the action of our thought, but 
is an active transformation of reality, generating new situa- 
tions, new concrete forms of existence, new orders of facts. 
Science does not confine itself to reflecting on something pre- 
sented to it from without, but it produces new bodies and 
phenomena, and realises modes of action that would not 
exist in nature without its work. 

In what does experimental verification consist? The 
physicist formulates an hypothesis and, taking it for guide, 
acts in the world of his experience. If he achieves the end 
proposed he asserts that the hypothesis is true. Otherwise he 
says it was false and modifies it. In the first place, if we con- 
sider carefully, an agreement has been attained between the 
actions of the physicist and the other innumerable activities 
of the world of his experience operating in that particular 
situation. That is, the physicist's actions and the other activi- 


ties have agreed, have worked in co-ordination, so as to 
obtain the result. 

The agreement of which we speak is not a resemblance, 
still less an identity of the acting forces. Each of these may 
have a widely different character from the others. It is 
enough that they should converge to the same end. It is a 
harmony of the kind that is realised in living organisms, 
where heterogeneous processes work in co-ordination so that 
the conservation of a given individual results. Concrete 
unity, therefore, not abstract identity: that is what the 
physicist produces, setting his theory to work in an experi- 
ment that confirms it. The varied action of the highly com- 
plicated apparatus in his laboratory, and through which the 
energies of the universe operate, and the activity of the 
human organism, in which thought manifests itself with its 
ideal conceptions, agree and work in co-ordination for the 
achievement of one and the same end, without loss of charac- 
teristic physiognomy to either. In scientific truth, this under- 
stood, intuition is not obliterated but enriched and poten- 
tialised. And, at the same time as intuition is enriched, the 
reality of experience attains an ever increasing harmony. 
The experimental action of scientific concepts renders reality 
more coherent; it composes forces in more regular rhythms, 
it installs an ever vaster and more perfect order. There is no 
work of man, there is no machine, in which this transforma- 
tion is not apparent. The electrical waves, for instance, en- 
gendered and received by human apparatus are produced 
with a greater regularity than that of those existing in a state 
of nature. And different energies, independent one of the 
other before our action, come to be combined in the 
physicist's instruments, so that he makes them co-operate in 
the attainment of the same end. 

Science, in short, is engaged in rationalising nature more 
and more. This must not be taken as if forces had been 
hitherto incoherent, but in the sense that there is process 
from a lower to an ever higher harmony. The physicist 
always starts from a situation that has a certain degree of 
coherence, but the new experiment aims at realising a more 


complete agreement between the forces involved, and at ex- 
tending it to others that had not previously been co-ordi- 
nated with these. We can speak of disorder in only a relative 
sense, that is, always in comparison with a higher harmony. 
When concrete rationality, that is to say, the progressive 
co-ordination of the activities of the world of our human 
experience to converge towards the same end, is thus under- 
stood, it is clear that there can be infinite degrees of ration- 
ality, of truth, of reality, in accordance with the greater or 
lesser vastness of the field of actions that reach agreement in 
a determined theory. Higher truth is characterised by a 
more comprehensive synthesis, and is that point of view that 
succeeds in embracing the partial truths of lower viewpoints, 
and of including in itself a greater wealth of intuitions. In 
respect of this higher form of rationality lower orders may 
be called relatively irrational, but one can never speak of the 
irrational in an absolute sense. However far back we may go 
we shall never reach an experience that does not comprise 
already some form of unity or rationality. There is no intui- 
tive life in which thought in a more or less embryonic stage 
is not immanent. Thought, like the life of experience, is not 
something derived. If we try to explain its genesis we pre- 
suppose it by the use of certain categories. The distinction 
between what is given and what is thought can only be rela- 
tive. Every scientific experiment, every philosophic reflec- 
tion, every activity of thought, starts from a certain initial 
situation which, in respect of that thought, of that reflection, 
however lofty, constitutes the relative datum. But this datum 
already contains the work of previous reflection or construc- 
tion. The fact from which the scientist starts in each new 
research is a certain situation of the world of experience, 
which has been already interpreted in terms of the logical, 
mathematical and physical theories of that historic moment 
and of the philosophic conception implicit in these. He does 
not start from the particular in order to rise to the universal 
law, as naive empiricism imagines, but from a given situation 
that is at once particular and universal. The problem of 
what was claimed to be the transition from the particular to 


the universal is badly set, and is therefore insoluble in the 
old terms. Induction is instead the transition from a certain 
logical order of experience to another richer and more har- 

It is as organs for realising this ever vaster and richer har- 
mony of the universe that the logical principles must be 
understood. They do not serve to assure an abstract identity, 
but they are rules for the co-ordination of our thoughts and 
intuitive activities in their convergence to a common end. 
Those ideas are practically equal for us that allow us to 
achieve this concrete agreement in our actions. The only 
possible verification of the relative identity of our concepts 
lies in experiment. We say that we have the same concept 
when in speaking or otherwise making use of it we succeed 
in reaching an understanding with other men or with our- 
selves. This does not exclude the concrete variety of 
thoughts, nor does it exclude change. It merely assigns cer- 
tain limits within which these variations must take place so 
as to enable the concrete agreement of our human activities 
and of all the activities of the world to be realised. The con- 
cept is not a simple essence that can be immediately intuited, 
either within our consciousness or beyond it; it is a construc- 
tive process, a complicated dynamism of relations, a more or 
less complex series of mental operations, which the word or 
sign serves to symbolise. The definition of the concept deter- 
mines the rules of this construction, the operations that must 
be carried out, the limits within which the activity of our 
thought must take place. But within these limits the process 
may assume an innumerable variety of forms both in our- 
selves and in other individuals, provided that a concrete har- 
mony of actions is obtained. 

This agreement is the aim of all logical structures and all 
mental categories, which are active constructions of our 
thought, and through which an ever vaster and richer co- 
ordination is realised between our activities and all the forces 
of the world. And thus the world, together with ourselves, 
is raised to a higher grade of concrete rationality. Like 
scientific theories, our philosophic syntheses must likewise be 


put to the test. For metaphysical ideas, too, are energies 
operating through our minds in the concrete reality of ex- 
perience, and in respect of them, as in respect of scientific 
concepts, we may ask ourselves if the actions they suggest or 
the modes in which, in their ensemble, they modify the 
forms of our activity, realise a higher harmony of the forces 
working in the world. 

Every philosophic conception is an endeavour to compose 
the activities of the universe in a richer harmony, to estab- 
lish an ever fuller rationality. There is no absolute rational 
order that our consciousness is compelled merely to mirror; 
instead, there is the realisation of ever more complete orders, 
with the vigorous collaboration of human thought. Phil- 
osophy is not Minerva's owl, which, as Hegel said, begins its 
flight only in the dusk. It does not reflect merely a develop- 
ment of logical categories already determined in the neces- 
sity of their process, but it also creates fresh categories. It 
constructs a higher grade of rationality which previously did 
not exist. It concentrates, in the experiment of its supreme 
synthesis, all the forces working in history, to make of them 
a single renovating energy. It is not a sunset in which the 
spirit recollects itself to reflect on deeds done, but the nascent 
dawn of new works the idea, the inspiration, of a history 
ever beginning anew. And history is precisely the laboratory 
for its continuous experiments, where it puts the efficacy of 
its constructions to the proof. The truth of a philosophic 
system cannot be decided by a priori reasoning, but lies in 
its concrete, historical function, in its action as the creative 
potency of a new rational harmony of the forces working in 
the world. Its truth is decided on the battlefields where the 
banners of old and new ideas are waving, and their age-long 
conflicts are composed in unpredictable agreements; in the 
revolutions which give birth to new civilisations; in the daily 
struggles, to which each man brings his whole thought, 
whether they be bloodless arguments or bloody encounters; 
in the book that works on souls and transfigures them, as in 
the ship that, crossing the oceans, brings continents together; 
in the parliamentary assemblies as in the fields and workshops; 


in political vicissitudes as in economic relations; in the public 
government of the State as in the intimate sanctuary of the 
family wherever a soul acts through the impulse of an idea. 
Every instant of history in its " concordia discors " fulfils the 
perennial experiment of our philosophic conceptions, which 
are relatively true only in the measure in which they make 
their efficacy felt in this fluid agreement of forces in conflict, 
which recomposes itself in forms that are always new. 

Thus rationality is not a fixed system of immutable prin- 
ciples and essences, not a persistence of abstract identities, 
but a concrete agreement constructed in its various degrees 
by the same process that engenders the life of history. It can 
assume an infinity of modes and forms that cannot and 
must not be predetermined. If rationality is thus envisaged, 
the craving that leads to irrationalism, the need to save the 
freedom of the spirit and the concreteness of experience, is 
satisfied. In fact, the whole fertile wealth of our intuitions 
and the possibility of ever new creations remain. And only 
so can the age-long antinomy between freedom and predes- 
tination, the product of the static and intellectualistic mode 
of conceiving rationality, be resolved. Only so is rationality 
in its dynamism equated to that infinite Power of creation 
that was the new word of Christianity. There is no system 
of intelligibles motionlessly present to the Mind of God. If 
that were so He would be the prisoner of His own eternal 
Thought. There would be no sense in speaking of creation, 
for in that Thought everything would have been already 
given. Divine Reason is not enclosed in any fixed order, but 
realises itself in infinite orders in the process of history, 
which is the work of at once man and God in intimate 
spiritual collaboration. And Providence is not a preformed 
design, but, in every instant of life, the creation of a new 
design that co-ordinates God always present and working 
our own human designs. 



Foreign Member of the Royal Society; President of the 
Kaiser Wilhelm Gesellschaft ; sometime Professor of Theo- 
retical Physics in the University of Berlin; Nobel Laureate 

THE recent developments in physics have shown that 
the high expectations of a deepening of the knowledge 
of nature which, in a certain degree, were rightly 
raised by the brilliant successes of physical research, must in 
essential points be reduced. In particular, the law of causality 
in its usual classical formulation can no longer generally be 
applied, because it has definitely been found to fail to apply in 
the world of atomic phenomena. It is necessary, therefore, 
that everyone who is interested in the meaning and impor- 
tance of physical research should make a new examination of 
the peculiar characteristics of physical law, and in particular 
should strive to penetrate more deeply towards the roots of 
the concept of causality. 

Today it is no longer possible to regard, with Kant, the law 
of causality as an expression of inviolable regulation which 
inheres in events, and is therefore a necessary framework in 
which experience comes to us, and without which experience 
is incomprehensible. In Kant's view certain modes of thought 
or categories are necessary for the conceiving of our experi- 
ences, and will remain the same for all time, but this does not 
assert anything about the nature of single categories. Kant 
regarded the axioms of Euclidean geometry as having the 
status of a category, and it is now known that not only is this 
category capable of extension, but even is in need of exten- 
sion. Physicists therefore are, consequently, now extremely 
cautious of accepting the finality of all such modes of thought 
and categories. In order to avoid prejudice we will bind our- 
selves by no dangerous assumptions and will therefore look 
for a reliable starting-point for the introduction of the con- 
cept of causality. 



In speaking of a causal link between two successive events 
we mean a certain connection, subject to law, between the 
two events, of which the earlier event is called the cause and 
the latter one the effect. But the question is, in what does this 
particular kind of connection consist? Is there any infallible 
sign proving a certain event occurring in nature to be causally 
conditioned by another? 

This question is as old as natural science, as old even as the 
whole or science, and that it continually arises proves it has 
not yet been finally answered. This unsatisfactory situation 
is mitigated by the fact that it could not be otherwise. For 
the expectation that the concept of causality could from the 
beginning have been formulated with complete precision and 
then applied to natural phenomena to see whether it fitted 
them, would in earlier times have appeared nai've, and today 
the development of exact research would make such an ex- 
pectation foolish. In natural science and other sciences we do 
not start with fundamental notions and then search for their 
realization in the world around us, but on the contrary pro- 
ceed from an examination of the world to the formulation of 
fundamental notions. As humans all of us through birth are 
set in the middle of a world in process of development. We 
are not previously prepared or informed of its nature, and in 
order to find our way in this life into which we have been 
obtruded we deal with our personal experiences as well as we 
can, while we form, with the help of the mental gifts with 
which we were born, certain concepts useful in describing the 
experience we have had, and therefore the experience which 
we shall have to expect. Much free-will and uncertainty 
obviously creep in with this procedure, as is proved by in- 
numerable events in every branch of science. Even in mathe- 
matics, the most exact of the sciences, the origin and nature 
of the fundamental ideas are disputed more intensively than 
ever before. If this can happen with mathematical ideas, 
nobody should expect that the concept of causality in nature 
can easily be settled in a manner accepted as valid for all 
times and states of knowledge. 

The never-abated and indeed now greatly increased interest 


of the thoughtful in the question of the nature and validity 
of the law of causality suggests that the concept of causality 
deals with something very fundamental, with something in- 
dependent of human minds and intelligence which has its 
roots deep in a reality not susceptible of direct scientific exam- 
ination. Few would doubt that if the earth and all its inhabit- 
ants suddenly perished the cosmic process would continue to 
obey causal laws, even if no one were there to observe the fact. 
Be that as it may, our only method of apprehending the 
essence of causality consists in studying the world or fact 
given to us that is, in studying our experiences. By profound 
consideration and generalization, and the utmost elimination 
of all admixture of anthropomorphical elements, we may 
slowly approach an objective concept of causality. 

The numerous investigations hitherto undertaken concern- 
ing this question show that the surest approach to a clear 
answer is obtained by connecting the question with the possi- 
bility of making correct predictions of the future. Indeed, 
for proving that any two events are causally connected there 
is no more unobjectionable means than that which consists 
in showing that from the occurrence of one event the occur- 
rence of the other event can always be concluded in advance. 
That was already known to the farmer, who demonstrated 
ad oculos to the incredulous peasants the causal connection 
between artificial manure and fertility of soil. The peasants 
refused to believe that the lush growth of clover on the 
farmer's field was due to artificial manure, and sought for 
other reasons. So the farmer had certain narrow furrows 
ploughed on his field; then he shaped them into letters and 
manured them profusely, so that after the shooting up of the 
seed the following sentence was legible in distinct clover- 
writing: "This strip of land has- been manured with 

As a starting-point for all further considerations I will 
therefore use the following proposition, applicable also 
beyond the domain of physics : An event is causally condi- 
tioned if it can be predicted with certainty. Thereby, of 
course, I only wish to say that the possibility of making a 


correct prediction for the future forms an infallible criterion 
for the existence of a causal connection, not by any means 
that the two mean one and the same thing. I need only recall 
the well-known example, that in the daytime we are quite able 
with certainty to predict the advent of night, yet day is not 
the cause of night. But on the other hand we often assume 
the existence of a causal connection in cases where there is no 
possibility at all of a correct prediction. Think of the weather 
forecasts ! The unreliability of weather prophets has become 
proverbial; and yet there is no trained meteorologist who does 
not look upon the occurrences in the atmosphere as causally 
determined. Thus we see that the original proposition chosen 
has only a provisional character. To reach the essence of the 
concept of causality we must sift matters more minutely. 

In the case of weather forecasts we may easily suppose that 
their unreliability is only conditioned by the size and the 
complicated nature of the object under consideration the 
atmosphere. If we take only a small quantity of it, say a litre 
of air, we shall far more probably be able to make correct 
predictions as to its behaviour under external influences, such 
as compression, heat, moisture and the like. We know certain 
physical laws which enable us to predict more or less posi- 
tively the results of the corresponding measurements, such as 
increase of pressure, increase of temperature, or condensation. 

On closer observation, however, we arrive at a very remark- 
able conclusion. Even if we choose ever so simple conditions 
and use ever such delicate measuring instruments, we shall 
never succeed in calculating in advance the results of our 
measurement with absolute accuracy; that is to say, not so 
accurately that it will agree with the measured number to the 
last decimal place. There always remains some residuum of 
inaccuracy, in contrast with purely mathematical calculations 
such as those of \/2 and TT, which can be stated exactly to 
any number of decimal places. And what applies to 
mechanical and thermal phenomena is valid for all regions 
in physics, including electrical and optical phenomena. 

Our experiences therefore compel us to recognize the 
following statement as a given and established fact : In not a 


single instance is it possible to predict a physical event 

On placing this fact side by side with the proposition, 
which served as our starting-point, that an event is causally 
conditioned if it can be predicted with certainty, we are con- 
fronted by a vexatious but unavoidable dilemma. Either we 
stick to the wording of the original proposition, so that there 
is not a single instance in nature in which a causal connection 
can be asserted, or we make room for the assumption of a 
strict causality, then we are compelled to subject our original 
proposition to a certain modification. 

There are nowadays a number of physicists and philoso- 
phers who have decided in favour of the first alternative; I 
will call them the indeterminists. According to them there is 
absolutely no real causality in nature no strict law. It is only 
an illusion given us by the appearance of certain rules which 
are never absolutely valid, although they are often very 
approximately so. On principle the indeterminist seeks a root 
of a statistical kind for every physical law, for gravitation, 
and for electrical attraction. For him they are all laws of 
probability, only relating to mean values from numerous 
homogeneous observations, and possessing only approximate 
validity for single observations, always admitting, therefore, 
of exceptions. 

The dependence of the pressure of a gas on the surround- 
ing sides of a vessel on its density and temperature is a good 
example for such a statistical law. The pressure is evoked by 
the impact of the random-flying molecules of gas against the 
sides of the vessel. The summation of the effects of these 
dynamical effects gives the result that the pressure on the 
sides of the vessel is nearly proportional to the density of the 
gas and the mean square of the speed of the molecules, which 
is in satisfactory agreement with experimental measurements, 
if one regards the temperature as a measure of the speed of 
the molecules. 

This theory is directly confirmed by investigating the fluc- 
tuations with time in the pressure on a very small portion of 
the sides of the vessel. If we observe a very small part of a 


side of the vessel, say the billionth of a square millimetre, a 
long time may pass before a molecule hits it. But it may also 
happen that two or even three molecules may come soon after 
each other. Under these conditions there is not a constant but 
a fluctuating gas pressure. The simple law of pressure is valid 
only for large areas of the sides of the vessel, upon which a 
vast number of molecules impinge, so that irregularities 
cancel out among themselves. 

Since molecules by their impacts always disturb mobile 
bodies when they impinge on them, they manifest them- 
selves in the phenomenon first described by Brown and 
named after him. Fine particles suspended in liquids may 
be observed under a powerful microscope to oscillate con- 
tinually. They are pushed to and fro by the molecules of 
liquid which impinge on them. A similar effect is observed 
with very sensitive balances for measuring weight. These 
never come to complete rest, but perform incessantly slight 
irregular oscillations about the position of equilibrium. The 
phenomena of radioactivity provide a further example of 
statistical law. Owing to its spontaneous disintegration, a 
radioactive substance incessantly emits a multitude of posi- 
tively and negatively charged particles. For longer periods of 
time one may speak of a steady rate of emission, but for 
shorter periods comparable with the time between the emis- 
sion of constructive particles the emission is completely 

As in the cases of the laws of gases and radioactivity, the 
indeterminists wish to attribute all other physical laws ulti- 
mately to chance. For them nature is governed by statistics 
alone, and their aim is to base physics on the calculus of 

But in fact the science of physics has hitherto developed on 
the opposite basis. It has chosen the second of the two alterna- 
tives : that is to say, in order to be able quite strictly to main- 
tain the law of causality, it has slightly modified the starting- 
point, which was that an event was causally conditioned if it 
could be safely predicted. The modification consists in using 
the word " event " in a slightly altered sense. It is not to one 


single actual measurement, always containing casual and un- 
essential elements, that the theoretical physicist gives the 
name of event. He reserves this name to an imagined pro- 
cess, going on in another world : we will call it the " physical 
world-picture/' which is substituted for the actual one given 
by our senses and by measuring instruments acting as a kind 
of refined sense. The physical world-picture is a mental con- , 
struction, arbitrary to a certain extent; an idealization, 
created for the purpose of escaping from the uncertainty 
which inheres in every individual measurement, and of be- 
coming able to establish sharply defined conceptual relations. 
In physics, therefore, all measurable quantities lengths, 
intervals of time, masses, charges and the rest have a double 
meaning, according as to whether we consider them as given 
directly by measurement or as transferred into the physical 
world-picture. In the first meaning such quantities can only 
be defined inaccurately, and can therefore never be repre- 
sented by precise numbers. But in the physical world-picture 
they stand for definite mathematical symbols, which can be 
operated with according to strict rules. If in physics we make 
use of a trigonometric equation for calculating the height of 
a tower, then in speaking of the height we mean quite a 
definite thing, a well-defined quantity. Yet the actual measure- 
ment of the height does not furnish a definite quantity. Con- 
sequently the so-called true height of the tower is a different 
thing from the measured height. Exactly the same argument 
applies to the frequency of vibration of a pendulum or to the 
brightness of an incanaescent lamp. Likewise every universal 
constant for instance, the speed of light in empty space or 
vacuum, or the charge on an electron is a different thing 
from the actually measured quantities. In the first meaning 
it is absolutely precisely, but in the second only inexactly, 
defined. The clear and logical distinction between the magni- 
tudes and quantities of the world of sense and the similarly 
named magnitudes and quantities of the physical world- 
picture is absolutely indispensable for the clarifying of con- 
ceptions. Without this distinction a discussion about these 
questions is futile. 


Therefore it is wrong to state, as some do, that the world- 
picture of physics contains or ought to contain only directly 
observable quantities. On the contrary, directly observable 
quantities do not appear at all in the world-picture. It con- 
tains nothing but symbols. Besides, there are always in the 
w r orld-picture elements which for the world of senses have 
only a very indirect significance or none at all, such as ether- 
waves, partial vibrations, co-ordinate systems and the like. 
Such elements at first act as ballast, but they are put up with 
in view of the decided advantage afforded by the introduction 
of the mental world-picture. This advantage is that the world- 
picture enables us to carry through a strict determinism. 

To be sure, the world-picture always remains an auxiliary 
conception : what we are eventually concerned with is, of 
course, the events in the world of the senses and their 
approximately correct forecasting, which in classical theory 
is effectuated in the following manner. First, an object of the 
world of the senses, say a system of material bodies in any 
measured state, is symbolized that is to say, transferred into 
the world-picture. In this way a definite physical system in a 
definite initial state is obtained. In like manner the influences 
which are subsequently exerted upon the object from the 
outside are replaced by corresponding symbols in the frame- 
work of the world-picture. Thus we are provided with the 
external forces acting on the systems, or with the boundary 
conditions. By these data the behaviour of the system is for 
all time unambiguously defined and can be calculated with 
absolute accuracy from the differential equations of the 
theory. Thus the co-ordinates and the momenta of all 
particles of the system result in quite definite functions of 
time. Now if for any later time we transfer back into the 
world of the sense the symbols used for the world-picture, we 
obtain a connection between a later event in the world of 
sense and an earlier event in the world of sense. This con- 
nection can then be utilized for the approximate prediction 
of the later event. 

To summarize : While in the world of sense the prediction 
of an event is always affected by something of an uncertainty, 


in the physical world-picture all events follow certain defin- 
able laws; they are strictly determined causally. Therefore 
the introduction of the world-picture reduces the uncertainty 
in the prediction of an event in the world of sense, to the 
uncertainty of the translation of the event from the world 
of sense to the world-picture and vice versa. Herein lies the 
significance of the physical world-picture. 

In classical theory, without much bothering about this 
uncertainty, attention was concentrated on the elaboration 
of the causal view of what is going on in the ideal world- 
picture that is, how it has achieved its great successes. In 
particular, it has succeeded in finding a satisfactory interpre- 
tation for the irregular fluctuations mentioned above, which 
correspond to the pressure of a gas or to the Brownian move- 
ment an interpretation that was based on the assumption of 
strict causality. For the indeterminists no real problem 
existed here. As they seek irregularity behind every rule, 
statistical law is what immediately satisfied them. Therefore 
they content themselves with the assumption that the col- 
lision of two individual molecules, as well as the impact of a 
molecule on the side of the vessel, occurs only to statistical 
laws. However, there is as little conclusive reason for such an 
assumption as there is for assuming that, because the elec- 
trons gather on the surface in a charged conductor, the 
charge of an individual electron must be on its surface too. 
On the other hand, the determinists, who conversely seek a 
rule behind every irregularity, were led to the task of build- 
ing up a theory of the gas laws on the assumption that the 
collision of two individual molecules is strictly conditioned 
causally. The achievement of this task is the life-work of the 
great physicist Ludwig Boltzmann. It forms one of the 
greatest triumphs of theoretical research. For this theory 
leads to the statement confirmed by measurements that 
the average energy of the fluctuations around the position of 
equilibrium is proportional to the absolute temperature. And 
further, from the measurement of such oscillations for 
instance, those of an extremely sensitive torsion-balance 
this theory makes possible a remarkably accurate calcu- 


lation of the absolute number and mass of the colliding 

In view of these and other great successes, reasonable hope 
prevailed that the world-picture of classical physics would on 
the whole be equal to its task, and that the uncertainties re- 
maining after the transfer into and from the world of the 
senses would lose their importance as experimental methods 
improved in refinement. But with one stroke this hope has 
for all time been destroyed by the appearance of the ele- 
mentary quantum of action. 

As the quantum theory started from a study of the phe- 
nomena of heat and light, these may be considered first. It 
has been discovered from a variety of evidence that the 
energy in a ray of light of any particular colour is not trans- 
mitted continuously, but in single particles, named photons, 
whose size is dependent only on the colour of the light, and 
which fly forth in different directions from the source with 
the speed of light. This is in perfect agreement with the early 
corpuscular theory of light formulated by Newton. The 
photons ordinarily succeed each other so swiftly that the light 
which they constitute seems to arrive as a continuous stream; 
but if, through growing distance from the source, the light 
becomes feebler and feebler, the photons become more and 
more separated, as a jet of water breaks into a stream of 
drops of a certain size. It is characteristic of radiation that it 
diminishes in intensity, not by a diminution of the energy of 
the constituent photons, but by an increasing scarcity of 

It is easy to see that the application of the notion of caus- 
ality to such phenomena leads to serious difficulties. Let us 
consider, for instance, the behaviour of a ray of light which 
comes from a certain direction and impinges on a polished 
glass plate. A part of the light may be reflected and another 
part, perhaps three times as much, may be transmitted. We 
know by experiment that this proportion is not affected by 
the intensity of the light and is therefore independent of the 
number of photons in the ray. If very many photons strike 
the plate, say one million, a quarter of a million are reflected 


and three-quarters of a million are transmitted. But what 
will happen if a very feeble ray containing only one photon 
strikes the plate? This presents a serious dilemma, because it 
is impossible to say whether it should be reflected or trans- 

But there is worse to follow. In the previous example a 
solution might be found in the assumption that the uncer- 
tainty of the direction of the photon is due to ignorance of 
some unknown influence controlling the behaviour of the 
photon. The following example seems, however, to be quite 
hopeless. It is evident that certain colours may be preferably 
reflected and others preferably transmitted, because when 
white light falls on the glass plate the plate appears coloured, 
not only in the reflected, but also in the transmitted light. 
The classical wave-theory of light has completely explained 
that the light reflected at the front side of the plate interferes 
with the light reflected from the back side i.e., that these 
two reflected rays weaken each other according to the coinci- 
dence of a wave-crest of one ray with a wave-trough of the 
other ray. As the wave-length for different colours is different, 
this effect varies according to the colour. Experiment has 
shown that the observed variations are strictly in agreement 
with the calculated variations. Now what happens if a single 
photon strikes the glass plate? The photon must interfere 
with itself, and as it is indivisible that is, on classical views, 
impossible. Evidently these quantum phenomena are quite 
inexplicable in terms of the wave-theory of light. 

The position concerning the quantum theory in mechanics 
is not different from that in light. For the smallest quanta of 
mass, the electrons, are like photons in that they can inter- 
fere with themselves. An electron of a certain speed exactly 
corresponds in this connection to a photon of a certain colour. 
When it falls upon a crystal plate it is preferably reflected or 
transmitted, and the detailed results arise from a considera- 
tion of the wave-lengths corresponding to its energy. There- 
fore the question which way the electron shall go, just as in 
the case of the photon, is not only an unsolved, but an in- 
soluble, problem. 


The principal difficulty, which is concerned with the deter- 
mination of the place of an electron moving with a certain 
speed, finds its general expression in the uncertainty relation 
formulated by Heisenberg, which is characteristic of quantum 
physics. It states that the more accurately the position in space 
is measured, the more inaccurate is the measurement of the 
speed, and vice-versa. This is explained in the following way. 
We are able to measure the position of a flying electron only 
when we can see it, and therefore we must illuminate it 
i.e., we must let light fall upon it. But the light which falls on 
the electron gives it a shock and changes its velocity in an 
uncontrollable manner. The more accurately the place of the 
electron is to be measured, the shorter must be the waves of 
the illuminating light, and hence the greater the shock, and 
therefore the greater the uncertainty of the measurement of 
the speed. 

It stands to reason that this statement makes it on principle 
impossible to transfer with any accuracy into the world of the 
senses the simultaneous values of co-ordinates and momenta 
which play the predominant part in the world of classical 
physics. For the strictly causal view of the world this fact 
raises a difficulty, which has already led some indeterminists 
to affirm that the law of causality in physics is definitely dis- 
proved. However, on closer consideration this conclusion, 
which is due to confusion of the world-picture with the world 
of sense, must be called at least premature. For there is at 
hand, for overcoming this difficulty, a means which has often 
done excellent service in similar cases. It is the assumption 
that the question as to the simultaneous values of the co- 
ordinates and of the momenta of the particle has no meaning 
in physics. The law of causality must not be blamed for the 
impossibility of answering a meaningless question. The 
blame must rather be laid on the assumptions which have 
led to the putting of that question that is to say, on the 
assumed structure of the physical world-picture. And as the 
classical world-picture has failed, it must be replaced by 

In fact, this has been done. The new world-picture of 


quantum physics has arisen from the desire to render pos- 
sible the accomplishment of a strict determinism in spite of 
the existence of the quantum of action. For this end the 
material particle, which has hitherto formed the primary 
component of the world-picture, has had to be divested of its 
elementary character : it has been dissolved into a system of 
material waves, which form the elements of the new mental 
picture of the world. 

The world-picture given by the quantum physics stands in 
about the same relation to that of classical physics as the wave 
optics of Huygens to the corpuscular or ray optics of Newton. 
As the latter was sufficient for many cases, but failed in others, 
the classical or corpuscular mechanics appears as a special 
case of the more general wave-mechanics. Instead of the 
material point we have an infinitely small packet of waves 
i.e., a numerous system of waves which interfere with each 
other in such a way that they cancel themselves everywhere 
in space except when the material point is to be found. 

In general the laws of wave-mechanics are, as everybody 
knows, quite different from those applying to particles in 
classical mechanics. But the most important point is that the 
function which is characteristic for the material waves, the 
wave function or the probability function the name is irrele- 
vant here is completely determined for all places and times 
by the initial conditions and the boundary conditions. We 
can calculate it by quite definite rules, employing either 
Schrodinger's operators or Heisenberg's matrices or Dirac's 

The introduction of the wave function also solved the 
problem of how a single electron behaves when it strikes a 
crystal plate; whether it is reflected or whether it penetrates 
the plate. The electron cannot divide, but each of the waves 
acting in its place is able to divide, so that there is a possi- 
bility of interference of the parts of the waves, and this inter- 
ference proceeds according to definite laws. 

Thus we see that the world-picture in quantum physics is 
governed by the same rigorous determinism which rules 
classical physics. It is only that the symbols are different, 


and that we operate with other rules of calculation. Accord- 
ingly in quantum physics, as formerly in classical physics, the 
uncertainty in the prediction of events of the world of sense 
is reduced to the uncertainty of the connection between the 
world-picture and the world of sense; that is to say, to the 
uncertainty of the translation of the symbols of the world- 
picture into the world of sense and vice-versa. The fact that 
this double uncertainty is put up with forms the most im- 
pressive proof of the importance of the task of maintaining 
determinism in the world-picture. 

To the critical judge the price, paid for the salvation of the 
strict law of causality, must seem indeed high. Yet but a 
superficial glance enables us to recognize how very far in 
quantum physics the world-picture has diverged from the 
world of the senses, and how much more difficult it is to 
transfer an event from the world-picture to the world of the 
senses, or vice-versa, in quantum physics than it formerly 
was in classical physics. In classical physics the meaning of 
every symbol was immediately comprehensible : the position, 
the velocity, the energy of a particle could be stated more or 
less directly from the measurements. There was no evident 
reason fornot assuming that one should be able to reduce the 
remaining uncertainty below any limit, as the refinement of 
experimental methods progressed. On the other hand, in 
quantum mechanics the wave function yields no means what- 
ever whereby this function can be interpreted directly in the 
world of sense. There should be no delusion concerning the 
name " wave/' however suitable and illustratively chosen, as 
the meaning of this word in quantum physics is entirely 
different from that in classical physics. In classical physics a 
wave describes a certain physical phenomenon, a perceptible 
movement or vibrating field open to direct observation. But 
in quantum physics it describes only the probability for the 
existence of a certain condition. For that which is divided 
when a photon or electron impinges on a crystal plate to pro- 
duce the interference phenomena is not the photon or elec- 
tron itself, but only the probability for the existence of the 
individual photon or electron. This quantity represents a 


quite certain number of photons or electrons only if extremely 
many impinge on the plate. 

This circumstance has again incited the indeterminists to 
an attack upon the law of causality. And this time the attack 
seems to promise a positive success; for from all measure- 
ments nothing more than a statistical significance of the wave 
function can be deduced. But again the same loophole for 
escape is open to champions of strict causality. They assume 
that the question as to the significance of a definite symbol in 
the world of quantum physics for instance, a material wave 
has no definite meaning, as long as we are not at the same 
time told how to ascertain this meaning not told in what 
condition is the special instrument which is employed for 
transferring the symbol into the world of sense. We therefore 
also speak of the causal effect of this instrument. Thereby we 
imply that the inaccuracy under discussion is at least in part 
conditioned by the fact that the amount of the quantity to be 
measured depends in a certain manner, subject to law, on the 
nature of the measuring process. 

In fact, every measurement, whatever method may be used, 
brings in itself a more or less strong perturbation of the phe- 
nomena to be measured, as we have already seen in the 
previous example of flying electrons, whose path is disturbed 
by the light indispensable for observation and is disturbed 
the more as the lighting is made more precise. Thus if a 
certain material wave corresponds on one occasion with one 
process in the world of sense and on another occasion with 
another, the question of its sensory meaning is to be answered, 
not by observation of it alone, but only by observation of the 
reciprocal relation between it and the measuring instrument. 

With this auxiliary assumption the whole question has 
been led into channels the further course of which still 
remains dark. For now the indeterminists are justified in 
putting forward the question whether any sensible meaning 
can be attributed to the idea that the measuring instrument 
should exert a causal influence on the process to be measured; 
for any attempt to test this influence would require new 
measurements, which would involve a new causal interfer- 


ence and would therefore bring a new feature of uncertainty 
into the problem. Therefore it seems to be impossible in 
principle to divide the "process in itself" from the instru- 
ment with which it has been measured. 

And yet this objection does not finish the matter. For, as 
every experimental physicist knows, there are not only direct 
but also indirect testing methods. In many cases the latter 
have done good service where the former had failed. Above 
all, I wish to oppose the now widespread and seemingly 
plausible opinion that a question in physics is only worth in- 
vestigation if from the outset the fact that it admits of a 
definite answer is established. If the physicists had always 
followed this precept, the celebrated experiment of Michelson 
and Morley on the measurement of the so-called absolute 
velocity of the earth would never have been made. We should 
then perhaps not even today be in possession of the theory 
of relativity. So our efforts to ascertain the absolute velocity 
of the earth have proved exceedingly fruitful for science, 
although nowadays the question itself is almost universally 
considered to be meaningless. Then are we not justified in 
expecting even much greater profit from investigating the 
problem .of causality, the roots of which have certainly not 
been reached hitherto a problem quite pre-eminent in its 
fertilizing influence on research? 

But how shall we come to a decision? Evidently there is 
nothing for it but to take one's choice between the opposing 
standpoints, to adopt one, and then to see whether from this 
starting-point we attain valuable or useless results. In this 
respect we must welcome the fact that the physicists who are 
interested in this subject are divided in two camps, one in- 
clining to determinism, the other to indeterminism. As far 
as I see, the latter are at present in the majority. But it is hard 
to tell, and the situation may easily change in the course of 
time. In between there seems to be room for a third party, 
occupying an intermediate position. They attribute to certain 
concepts, such as electrical attraction and gravitation, an im- 
mediate significance and a strict rule of law, while ascribing 
to other concepts, such as the light-wave and the particle- 


wave, only a statistical significance for the world of sense. 
This notion, however, appears at the outset rather unsatis- 
factory on account of its want of uniformity. So I shall leave 
it aside and confine myself to the elucidation of the two 
absolutely logical standpoints. 

The indeterminist's yearning after knowledge is satisfied 
by the statement that the wave function of quantum physics 
is only a probability scheme; for him there is no further 
question to put. Also with the radioactive processes he is 
satisfied by the statement that, for instance, in any radioactive 
accumulation a certain average number of atoms disintegrate 
every second, but he does not ask why one atom disintegrates 
just now and a neighbouring atom perhaps a thousand years 
later. On the other hand, he looks upon a definite law of 
nature, such as Coulomb's law of electrical attraction, as an 
unsolved problem. He cannot content himself with Coulomb's 
law of force or potential, but must try to find exceptions. He 
will not be satisfied unless he succeeds in establishing what 
the probability is that the electrical force will diverge from 
Coulomb's law to any specified extent. 

The determinist takes the opposite view in all these 
matters. He is quite content to look upon Coulomb's law as 
an ultimate and fundamental law of nature. The interpreta- 
tion of the wave function as a probability function he will 
only admit as long as no account is taken of the particular 
apparatus with which the wave is generated or analyzed. He 
seeks relations strictly subject to law between what is going 
on in the bodies that interact with the wave and the form of 
the wave function. For this purpose he is, of course, obliged 
to begin by making the measuring apparatus as well as the 
wave function the object of his research. That is to say, he 
must transfer into his world-picture the whole experimental 
arrangement for generating the material waves for instance, 
the high-potential battery, incandescent wire, or radioactive 
substance and also the whole of the measuring apparatus, 
such as the photographic plate, ionization chamber, or Geiger 
counter, with all that is going on in them; he must treat all 
these objects together as one single system, as a closed unity. 


This, of course, is not sufficient to solve the problem, which 
on the contrary has become even more complicated. For 
since one is allowed neither to divide the total system nor to 
expose it to any interference from outside, lest it should lose 
its original character, no direct test whatever is feasible. On 
the other hand, it now becomes possible to set up certain 
hypotheses of a new kind with regard to the internal occur- 
rences, and then to examine their consequences. The future 
will show whether we are able to advance in this way; up to 
now we cannot distinctly discern in what direction progress 
will be accomplished. But this much may be safely affirmed : 
the elementary quantum of action sets an objective insuper- 
able limit to the sensitiveness of the physical measuring 
apparatus at our disposal, which will prevent us for ever from 
completely causal understanding of the minutest physical 
processes " in themselves " i.e., independently of their source 
and effects. 

This really brings us to the end of our considerations. They 
have shown us that the standpoint even of modern physics 
does not prevent us from achieving a strictly causal view 
the word " causal " being understood in the modified sense 
explained above although the necessity for such a view can 
be proved neither from the outset nor afterwards. Yet even 
the convinced determinist and he, perhaps, more than any- 
body else is overcome by a scruple which hinders him from 
being quite satisfied with the interpretation of causality intro- 
duced here. For even if we should succeed in further develop- 
ing the concept of causality on the lines laid down, it would 
be affected by a grave deficiency. One might suppose that a 
relation of so deep a significance as the causal connection 
between two successive events would in its essence be inde- 
pendent of the human mind which considers it. The reverse 
is true. At the outset we had to attach the concept of causality 
to the human intellect, with reference to the capability of 
predicting an event; furthermore, we were not able to enforce 
the adoption of the deterministic view otherwise than by 
substituting for the given world of our senses the physical 
world-picture. The latter is a creation of human imagination 


of a provisional and changeable character. Anthropomor- 
phisms of that sort are ill-suited to form a fundamental 
physical concept. So the question arises whether there is no 
way of giving the concept of causality a deeper significance 
by divesting it as much as possible of its anthropomorphic 
character and by making it independent of the introduction 
of an artefact, such as the physical world-picture, but directly 
connected with the experiences in the world of sense. We 
must, of course, retain our original proposition, that an event 
is causally conditioned if it can be safely predicted; other- 
wise we shall lose our only foothold. But we must also adhere 
to the second proposition, that in not a single case is it possible 
to predict an event exactly. It then follows, as before, that in 
order to be able to speak of causality in nature we must apply 
some modification to the first statement. So far everything 
remains as it was. But the modification we had applied above 
can be replaced by one of quite a different kind, in one sense 
quite an opposite modification. 

What we modified here was the object of prediction, the 
event. We did not refer the events to the immediately given 
world of the senses, but to the fictitious world-picture. Thus 
we were able accurately to determine the events. But instead 
of the objects we may modify the subject of prediction, the 
predicting mind. For every prediction necessitates the exist- 
ence of a predictor. In the following we shall therefore limit 
our attention to the predicting subject, and look upon the 
immediately given events of the world of sense as the object 
of prediction, without introducing an artificial world-picture. 

It is obvious that the certainty of the prediction depends in 
a high degree upon the individuality of the predictor. Let us 
again refer to weather forecasts. It is evident that it makes a 
great difference who provides us with the forecast for to- 
morrow whether it is an ignorant person, who knows 
nothing about today's atmospheric pressure, direction of the 
wind, atmospheric temperature and humidity, or a practical 
farmer, who has noted all these data and has a wide experi- 
ence, or again a scientifically trained meteorologist, who be- 
sides the local data has at his disposal numerous weather- 


charts from all parts with exact information. With each of 
these successive prophets the uncertainty of the prediction is 
more and more diminished. It is therefore an obvious thought 
to assume that an ideal mind, apprehending everywhere all 
the physical occurrences of today in their minutest points, 
should be able to predict with absolute accuracy the weather 
of tomorrow in all its details. And the same argument can be 
applied to every other prediction of physical events. 

Such an assumption means an extrapolation, a generaliza- 
tion, which can neither be maintained by a logical conclusion 
nor refuted a priori. It must therefore not be judged accord- 
ing to its truth, but rather according to the value that is in- 
herent in it. In the light of this view, the actual impossibility 
of accurately predicting an event in even one single case, 
either from the standpoint of classical physics or from that 
of quantum physics, is a natural consequence of the circum- 
stance that man with his senses and his measuring instru- 
ments is a part of nature. He is subject to her laws and can- 
not escape from her, while such a tie does not exist for the 
ideal mind. 

The objection that this ideal mind is only a product of our 
thoughts, and that our thinking brain also consists of atoms 
following physical laws, is not able to withstand a closer test. 
For it is indubitable that our thoughts can lead us beyond 
every law of nature known to us, and that we are able to 
imagine relations which transcend the realm of physics. He 
who would assert that the ideal mind could exist only in 
human thoughts, and would disappear from life when the 
men that think the thoughts disappear, must also assert that 
the sun, like the whole of the external world, can exist only 
in our minds as the only source of scientific knowledge, while 
every reasonable man is convinced that the sun, even if the 
whole of mankind were extinguished, would not in the least 
lose its illuminating power. We believe in the existence of a 
real external world, though it withholds itself from direct 
observation. In the same way nothing prevents us from be- 
lieving in the existence of an ideal mind, though it will never 
make itself an object of scientific research. 


We must not consider the ideal mind akin to us, and must 
not demand of it how it procures the knowledge enabling the 
exact prediction of future events. For the inquisitive ques- 
tioner might easily, like Faust, be awed by the answer: 
" Thou'rt like the spirit which thou comprehendest, not me ! " 
And if the questioner nevertheless remains obdurate and 
declares that the notion of an ideal mind, if not illogical, is 
yet empty and superfluous, he must be met with these argu- 
ments: Not all statements eluding logical reasoning are 
scientifically valueless, and such a short-sighted formalism 
chokes up the source at which men like Galilei, Kepler, 
Newton and many other great physicists have slaked their 
scientific thirst for knowledge. For all these men, consciously 
or unconsciously, the devotion to science was a matter of 
faith, of unwavering faith in a rational scheme of the 

It is true this faith can be forced upon nobody, just as one 
cannot command truth or forbid error. But the simple fact 
that up to a certain degree we are able to subject future 
natural events to our thoughts and to guide them at our will 
would remain a complete riddle if it did not at least point to 
the existence of a certain harmony between the outer world 
and the human mind. And the question to what depths one 
imagines the sphere of this harmony to be extended is only 
of secondary importance. In any case, the completest har- 
mony and therewith the strictest causality rests in the 
assumption of an ideal mind, which sees through the 
laws of nature besides the phenomena of the intellectual 
life, down to the minutest detail in present, past and 

But how does this affect the freedom of the human will? 
Will this not be abolished, and man therewith degraded to a 
bloodless automaton? This problem is too near and too im- 
portant to be dismissed without a few words of discussion, 
although I have already had occasion to define my position 
regarding it. In my opinion there exists not the slightest 
contradiction between the reign of a strict causality, as in the 
views here expounded, and the freedom of the human will. 


The law of causality and the freedom of the will refer to 
quite different questions. While, as we have seen, the under- 
standing of a strict causality in the world's process needs the 
assumption of an ideal all-seeing mind, the question whether 
the will is free or not is an affair only of self-consciousness, 
thus can be decided only by the self. The concept of free-will 
means only that man himself feels inwardly and mentally 
free, and whether this is the case only he himself can know. 
That is not in contradiction with the view that the motives of 
his will can be thoroughly discerned by an ideal mind. He 
who feels himself restricted in his moral dignity by such an 
idea forgets the enormous superiority of the ideal mind over 
his own intelligence. 

The most remarkable proof of the independence of one's 
will from the law of causality is seen when, in order to in- 
crease self-knowledge, one tries to predetermine, with the help 
of the law of causality, the activities and motions of one's 
will. Such an attempt is from the beginning bound to fail, 
because every application of the law of causality to the will 
would produce knowledge of the will which would itself act 
as a motive and thereby always change the result. Therefore 
it is thoroughly mistaken to say that the impossibility of 
causally predetermining our activities is due to lack of under- 
standing which perhaps later, through a tremendous increase 
of intelligence, would be removed. That would correspond to 
the assertion in physics that the impossibility of exactly deter- 
mining at the same time the position and speed of an electron 
is due to the incompleteness of the observations. No, the 
impossibility of deriving our future activities purely causally 
is not due to lack of understanding, but to the simple con- 
dition that no method which transforms an object is suitable 
for examining it. The thinking man, therefore, never can 
make the authoritative decision through the law of causality, 
but only through a quite different law, the moral law, which 
grows in a special ground and is not to be apprehended by 
scientific methods alone. Scientific thinking requires always 
a wide and sharp difference between the thinking subject and 
the studied object, and this distance will be guaranteed best 


by the assumption of an ideal mind which can be considered 
only as a subject and never as an object. 

May not the prohibition against the ideal mind an object 
of thought involve an unsatisfactory renunciation, so that the 
accomplishment of a strict determinism is too dearly pur- 
chased? However this may be, the price is less than the in- 
determinist must pay for his view of the world, as he must 
cease at a much earlier point his quest for knowledge, because 
he must renounce from the first the possibility of certain laws 
valid in special cases, a degree of resignation which is so 
astonishing that one would have to ask why determinism 
nowadays has so many followers among the physicists. If I 
am not mistaken, the explanation lies in the psychological 
sphere. When a new great idea appears in science it is tested 
in all directions, and if it is proved to be fruitful one tries to 
make it the foundation of a comprehensive and closed system 
of ideas; thus it was with the theory of relativity, and now it 
is with the quantum theory. As quantum physics at present 
culminates in the wave function, one tries to give this a final 
significance. As the wave function has the significance only 
of a measure of probability, one tries to make the question of 
probability the final, deepest problem, and therewith makes 
the concept of probability the foundation of the whole of 

I do not believe that in the future these questions will ever 
be solved. For if in spiritual spheres, whose laws possess even 
more the character of probability, no single event can be 
exactly determined if the causal source is not made clear, the 
problem of causality is much less likely to be eliminated from 
natural science. 

The law of causality is neither right nor wrong, it can be 
neither generally proved nor generally disproved. It is rather 
a heuristic principle, a sign-post, and to my mind the most 
valuable sign-post we possess, to guide us in the motley con- 
fusion of events and to show us the direction in which scien- 
tific research must advance in order to attain fruitful results. 
As the law of causality immediately seizes the awakening 
soul of the child and causes him indefatigably to ask " Why?" 


so it accompanies the investigator through his whole life and 
incessantly sets him new problems. For science does not mean 
contemplative rest in the possession of sure knowledge; it 
means untiring work and steadily advancing development 
towards an aim which we are able to imagine but never to 
reach intellectually. 

[Part of the argument in this essay is also contained in the 
"Guthrie Lecture" by Professor Planck, delivered before 
the Physical Society in London on June iyth, 1932, and 
which was published in Volume 44, Part 5 (1932), of the 
Proceedings of the Physical Society.] 


By A. E. HEATH, M.A. 

Professor of Philosophy in the University College of Swansea 

MODERN scientific developments have had less 
direct influence upon the character, as opposed to 
the matter, of philosophical thought than is com- 
monly supposed. Even recent advances in the maturer 
sciences like physics and astronomy, revolutionary as they 
seem, only turn out on inspection to raise problems of the 
same type as those which have haunted philosophers through 
the ages. Nevertheless there does seem to be, in our time, a 
perceptible drift of opinion in philosophy which, whilst not 
constituting a single unified outlook, yet creates a definite 
modern temper and a temper whose cool austerity owes 
something indirectly to that same quality in scientific 
thought. It is not easy to describe: but appears in the 
methods of work of the most outwardly diverse thinkers, and 
is steadily becoming stronger and more explicit. The pro- 
duct (like so much in our day) of both disillusion and hope, 
it combines constructive discretion with analytical vigour. 

Philosophy, at its best, has always been a more than usually 
resolute attempt to see the world clearly, and see it whole 
an attempt that is to say, to be both critical and constructive. 
It is in criticism that its more enduring value has lain; but it 
is construction which has given it prestige. The modern 
philosophical temper is one which is anxious to earn its 
unities, to return full value for any prestige which may 
accrue to it. It is an attitude of mind which is impatient of 
constructions built on gaps in our knowledge, or achieved by 
slurring over differences instead of by hard critical endeavour. 
In short, the emphasis is upon analysis rather than synthesis 

369 24 


an emphasis so decided that most modern philosophers, 
even those who believe it may be possible in the future, hold 
that the time is not yet ripe for anything which could strictly 
be called metaphysical construction. Not that synthesis is 
despised. On the contrary, in a world of rapid change like 
our own, involving the breakdown of earlier unities, new syn- 
theses are a crying need. But that only makes systems more 
suspect to the philosopher. The objective unities he hopes 
for must not be mere wish-fulfilments. 

A word of explanation is necessary here. Though we may 
think (in spite of the valued system-building of McTaggart 
and Alexander) that construction of a strictly philosophical 
kind is beyond our powers at the present time, it may still 
be legitimate to attempt something short of this some 
bringing together of the separate parts of our knowledge into 
a possible, if not provable, unity. This would constitute 
what I should prefer to call ' Synoptic Science * rather than 
philosophy. If anything of this kind is undertaken, we shall 
have to distinguish clearly between the two sides of our 
enterprize between our critical labours and our constructive 
hopes. Criticism is individualistic. Construction is compli- 
cated by the fact that it is a social, as well as an intellectual, 
need. Critical power is born of plastic intelligence and bears 
the mark of its origin, being irresponsible because so re- 
sponsive to change; it plays light-heartedly over our most 
cherished cultural systems. Constructive capacity, as used in 
the past for building unities within which men might live 
significant lives, is related rather to knowledge than to intel- 
ligence; and it is notorious that learning, mere weight of 
knowledge, is readily harnessed to prejudice or to social 

That is why no synoptic view worth the name can possibly 
be achieved without including human studies (biological, 
psychological, sociological) in its scope. These less mature 
sciences have not, as yet, received the attention they deserve 
from philosophers, who have been dazzled by the brilliant 
achievements of physics. Before we can attempt new unities, 
in a world distracted by partial views and specialist incon- 


sequence, this deficiency must be made good. But it may 
well be that human studies will have to advance much fur- 
ther before we dare entertain any such ambition. It is only 
through understanding that our animal activities become 
arts. And perpetual progress in understanding is not, ac- 
cording to Prof. C. D. Broad, inevitable. It is only a possi- 
bility and one which is dependent on our acquiring an 
adequate knowledge and control of life and mind before the 
combination of ignorance on these subjects with knowledge 
of physics and chemistry wrecks our whole social system. 
" Which of the runners in this very interesting race will win, 
it is impossible to foretell. But physics and death have a long 
start over psychology and life/' 

The first question we will take up is whether a process in- 
volving ideals of explanation which vary from age to age, 
like fashions, does not vitiate the supposed objective char- 
acter of science at its source. Everyone now recognizes how 
all-pervading the act of selection is in scientific work. The 
scientist chooses his facts; he selects from a range of possible 
laws; he picks out the hypotheses which best conform to his 
body of more generalized theories; and finally he comes to 
realize that there has been an element of choice in his 
general theory-systems determined by his ideals of explana- 
tion. Yet at no stage in this hierarchy does he lose sight of 
objective reference. 

The scientist selects his facts in order to produce the 
widest possible co-ordinating hypotheses, though the facts 
must be there to choose from. He chooses also his laws, 
generally on the grounds of simplicity. Dr. Norman Camp- 
bell has brought out this arbitrary element in scientific laws. 
The * truth ' of a law, according to Dr. Campbell, depends on 
its fitting the observations; but its ' meaning ' comes from the 
intellectual satisfaction which the particular law chosen 
affords. The laws of science, then, are chosen from among 
other possible laws because they fit into theories " the form 
of which is dictated chiefly by preconceived ideas of what a 


theory should be." This introduces a conventional element 
which often determines the type of laws characterizing an 
age or a country. Nevertheless, we must not forget that if 
any law can be shown to be ' untrue ' it will at once be re- 
jected, however much 'meaning' it may have. Again, 
theories and theory-systems, the next stage in this series of 
levels, are subject to choice. Here, also, we must be careful 
to avoid assuming that a bare and arbitrary element of per- 
sonal choice is involved. It is not nearly so simple as that. 
Dr. Dorothy Wrinch-Nicholson has put the whole matter in 
regard to these wider and more generalized theories with 
admirable clearness. She showed that the unusual assump- 
tion of a discrete series of states for a physical system, made 
necessary by quantum theories, can be put in terms of ab- 
stract properties of the relation between different states of a 
single physical system. The choice between a discrete and a 
continuous series of states can be related to the general char- 
acteristics of compact and well-ordered serial relations. As so 
often happens, she says, the cogency of our objections, which 
come from the initial strangeness of the ideas, disappears as 
soon as those objections are stated in their most fundamental 
terms. " Physical intuitions " she continues, " as to whether 
very complicated and obscure relations are discrete or com- 
pact are clearly, if I may say so, out of place. We have to 
assume to be true, whatever fits the facts of experience most 
adequately ". 

There is thus, at every stage in this series of selective pro- 
cesses, an objective reference which purges the choice of 
anything arbitrary or personal. Viewing the bewildering 
range of choice, and the litter of discarded facts, laws, and 
theory-systems, a critic might exclaim with Mr. Sullivan: 
" To judge from the history of science, the scientific method 
is excellent as a means of obtaining plausible conclusions 
which are always wrong, but hardly as a means of reaching 
the truth." What the critic would overlook would be the fact 
that earlier work is never entirely discarded. There is always, 
as Mr. Sullivan is quick to point out, a part which is incor- 
porated in the next advance. There is a real sense in which 


the scientist (to use a phrase coined by Mr. E. M. Forster 
for a very different purpose) is at an angle with the universe : 
the man who is always immediately in the wrong because he 
is ultimately in the right. It must be remembered, however, 
that the ' ultimately ' refers to the end-point of a long series. 
When Clerk Maxwell constructed his great variety of 
mechanical analogues he put them forward as being simply 
scaffolding (a means of readily dealing with the electro-mag- 
netic phenomena to which they are analogous) to be dis- 
carded as soon as he had constructed, with its aid, his great 
generalizations. We must not take the scaffolding too 
seriously or we shall fail to notice the building : the scaffold- 
ing is nothing more than an aid to investigation. We may 
be forgiven, therefore, if we look with a sceptical eye at the 
hypostasization of ordering conceptions and at the kaleido- 
scopic series of world-pictures founded upon them. When, 
for instance, Sir James Jeans (combining Galileo's concep- 
tion of God as the great Geometer with the more subjec- 
tive part of Berkeley s mentalism) talks about the universe 
as consisting of the thought of a mathematical thinker, we 
need not take it too literally. It should be accepted only as a 
suggestive metaphor on the same level as the description of 
architecture as " frozen music/' 

We may now turn to the process of abstraction by which 
we reach our knowledge of structures. Abstraction is an old 
subject of philosophical debate, of course. But there are 
reasons for believing that some of the earlier misconceptions 
can now be avoided, in light of its more deliberate and 
thoroughgoing employment in recent developments, and of 
the enormous advance in its technique. It is necessary to 
deal briefly with the function of abstraction in science be- 
cause this brings out, as nothing else can, the changed intel- 
lectual climate of scientific thought. It seems clear, for 
instance, that abstraction is neither mere increase in our dis- 
crimination of what was already known in a concrete setting; 
nor bare omission, and hence falsification. For in the first 
place scientific abstraction gives genuinely new knowledge, 
supplied in experience but not necessarily of itself expe- 


rienced, in such matters as the atomic constitution of bodies, 
the pre-human history of the earth, and so on. And secondly, 
scientific abstraction as we have seen it at work, is plainly 
integrative and not separative in character: its fruits are 
structural syntheses. Philosophers are alive to this. Prof. 
Kemp Smith insists that abstraction is more than a methodo- 
logical device, like a microscope, for studying the partial 
features of a whole : it is also a recognition of u identities in 
experience that would otherwise remain in isolation/' In ab- 
straction " we are obtaining a knowledge of more than the 
separate items that make up the real world; we have made a 
beginning in the task of deciphering what is equally impor- 
tant, its structural pattern." So that besides the enlargement 
of our sense of possibilities which structural knowledge 
brings, there is freedom from the hesitations induced by 
the common but unfounded fears that abstractive analysis 
might be either falsification or productive of only ' partial ' 
truth. Science has become both less dogmatic and more 

That function of the abstract which plays a great part in 
its f ruitf ulness has still, however, to be mentioned : namely, 
that " it makes possible apprehension of its counterpart, the 
uniquely individual". Increased knowledge of structure 
brings in its train deeper sensitiveness to individual differ- 
ences. We do not start with what is individual: that is as 
much the product of analysis as structure. Now this sense 
of uniqueness which is, as it were, a by-product of abstrac- 
tion also acts as a further check on dogmatism. It makes 
men more alive to what Clerk Maxwell called ' singularities ' 
in nature. Perhaps that is why men of science nowadays 
can face with equanimity such astonishing possibilities as 
that causal law may not wholly apply to atomic phenomena, 
or that electrons may be organisms. If singular points do 
disturb the deterministic calm of our equations, it need not 
mean the breakdown of law but only its limitation to other 
than the unique. No doubt obscurantists will find in this 
situation a ground of appeal against all forms of law : but 
the reply to them is, clearly, that our sense of these singu- 


larities only advances with, and is dependent upon, increase 
in the range of our structural knowledge. 

We need to be careful not to build upon mere provisional 
absence of law. The last word has probably not yet been 
said about quantum theory. And even as it stands, all that 
the "Principle of Indeterminacy" really asserts is that "a 
particle may have position or it may have velocity, but it 
cannot in any exact sense have both." Or to put it in 
another way, you can only see an electron when it emits 
light, and it only emits light when it jumps; so that to see 
where it was you have to make it go elsewhere. Now as 
Dr. J. E. Turner has pointed out, there is a sense in which 
a quantity is ' determined ' when it is measured. But all the 
arguments in favour of " free will among atoms " rest on the 
fallacy of equivocation which substitutes quietly the other 
sense of 'determined', that in which a quantity is said to 
be determined when it is caused. Our view on the wider 
question as to whether everything in the universe is deter- 
mined will depend on what we take causality to be. But 
that is a subject which goes beyond atomic physics and 
involves the nature of law in general. For the moment let 
us glance at a narrower question : namely, as to whether 
laws in all the sciences are ultimately reducible to the laws 
of physics. 

It is often stated that materialism has been killed by 
modern physics. This report is "grossly exaggerated/' 
Materialism is more alive than ever; but it now takes the 
form of asserting that, in the last resort, the course of nature 
is determined by the laws of physics. Our view of this will 
depend on our attitude to the so-called 'emergent' proper- 
ties of complexes. If these are ultimately irreducible (as 
Broad, Lloyd Morgan, Smuts and Alexander believe) then 
the sciences will keep the autonomy they now possess. But 
again, we must not build on ignorance, on the present gaps 
in our knowledge. If (as Bertrand Russell and Einstein be- 
lieve) emergent properties indicate mere scientific incom- 
pleteness, then the day may come when the various sciences 
will finally form a hierarchy in which the primitive concepts 


of each science are the derived concepts of the science logic- 
ally prior to it a consummation which expresses the work- 
ing faith of most men of science. I imagine that this ques- 
tion will not be decided until our analysis of the whole 
notion of emergence and its implications has been carried a 
good deal further than it has now gone. For the moment 
we must content ourselves with saying that the world is less 
of a ' unity ' if the first view holds than if the second is true. 
The one makes the world a plurality of irreducible wholes 
(as on Lloyd Morgan's view, or Smuts' ' holism '). The other 
makes it a single system. But even to those who hold the 
second view, a still more radical doubt supervenes : namely, 
the doubt as to whether causal laws are anything more than 
regular sequences between concrete events which induce 
confident expectations about the behaviour of the universe, 
but from which we cannot, in the strict logical sense, infer 
that it is a rational whole. We shall return to this more 
ultimate question later. For the present, a subsidiary diffi- 
culty faces us : namely, the question as to whether the laws 
of science really do tell us anything about the actual rela- 
tions in the universe which their structure indicates. Broadly 
speaking, from sets of laws we can infer a structural order; 
but structures are generated by relations. Can we find out 
what the actual generating relations are? 

It is clear that one result of the change towards greater 
abstractness in physics has been to widen the gulf between 
the structure revealed in its generalizations, and the 
observations from which they arise and to which they 
are referred. A number of thinkers hold the view that, in 
its mature modern form, field physics tells us nothing about 
the external world but the structure indicated by causal 
laws. (And the day may come when atomic physics, in the 
hands of a Dirac, may achieve the same character.) Now 
logically, our knowledge about structure consists only of the 
kind of things a blind man could be told about a picture. 
The mere existence of a given structure (indicated, of course, 
by physical observations) tells us nothing in itself about the 
generating relations involved. Consider the world as a four- 


dimensional aggregate of point-events and suppose that 
there exists a system of relations, with the world as field, 
giving the particular structure indicated by physical laws. 
Then systems of relations differing from these can be found 
which would nevertheless give the assigned structure. A 
variety of ' interpretation ' is therefore possible, and choice 
must be made according to some criterion. It was probably 
considerations of this kind (and overlooked by some of his 
critics) which led Eddington to suggest that all the laws of 
classical physics, like the conservation of energy, boil down 
to nothing but conventions as to measurement; and that 
our choice depends on that predilection for ' substantial 
analysis ' whose role in the development of physics is now 
commonly recognized. From that it is but a short step to re- 
garding substance as ' categorial ' in the Kantian sense. The 
footprint we find in the sand is our own. 

Apart from the fact that it is very unlikely that we shall 
return to any form of Kantianism, there is another way 
open to us of avoiding the conclusion that, because there is 
an arbitrary choice, nothing objective is known. If our 
common-sense experience merely leads us up to the structure 
of law, but not to the relations generating it, then we are as 
much debarred from knowing the realities of the world as 
we were when our picture of it was painted in the early bad 
manner of Eighteenth Century billiard-ball materialism. 
But we might insist from the outset (as I have hinted before) 
that we are not standing blindly before the picture. We see 
it, and do not need an interpreter making arbitrary or con- 
ventional choice : that, in short, the realities of the external 
world including our fellows are, to say the least, as much data 
of knowledge as the disembodied sense-data and isolated 
structures which we analyse out of common-sense experience. 
This is not quite the way taken by Prof. Whitehead in his 
radical denial of the "bifurcation of nature"; but he does 
hold that both particulars and structures are equally ab- 
stractions from the concrete flux of the " actual occasion ". 
We commit the fallacy of misplaced concreteness if we for- 
get their character as abstractions; yet both are as genuine 


characteristics of nature as the flux out of which they arose. 
This type of solution amounts in Whitehead to a return 
to immediate experience in all its concreteness : a step taken, 
in reaction from difficulties over structural systems, by 
modern philosophers as widely different as Bergson and Brad- 
ley though for different purposes. The one to replace 
organized understanding with the way of immediate in- 
tuition; the other to avoid the "spectral woof of impalpable 
abstractions " by a new beginning in " an immediate feel- 
ing, a knowing and a being in one/* What I had in mind, 
when speaking of standing before the picture, was not this 
step, but a return simply to our starting-point in perceptual 
judgments themselves: and an insistence that statements 
expressing these form the basis for both (a) scientific treat- 
ment, and (b) philosophical analysis. Science adds to such 
statements of fact; philosophy, instead of explaining them 
away, analyses them in the sense of finding out the structure 
of that to which reference is made if they are true. The sort 
of view here indicated is the product of several lines of 
thought. It has special interest for the student of science, in 
that it induces a more ready acceptance of common-sense 
fact in all domains since its aim is to analyse facts, not to 
justify them. For that reason we must look at it more closely. 

We all make perceptual judgments and express them in 
statements, such as the proposition (to use Prof. G. E. 
Moore's example) that "The earth has existed for many 
years past/' Moore suggests that the reason philosophers 
have so often hesitated to admit that this is the very type of 
an unambiguous expression, the meaning of which we all 
know, is that they confuse two senses of the phrase 'we 
know what it means'. The first of these senses is that we 
understand the proposition sufficiently to use it in ordinary 
human discourse. But this is entirely different from the 
second: that we know what the proposition means in the 
sense that we are able to give a correct analysis of its meaning. 

This distinction is fundamental in Moore's thought, and 


in the work of the many thinkers who have been directly or 
indirectly influenced by him. Perhaps a rough analogy 
drawn from scientific practice will make it clearer. Many 
mathematical notions, such as that of continuity, are made 
practical use of, long before they receive satisfactory logical 
definition. The successive definitions are at each stage pushed 
to the limit of their functional value, closer definition fol- 
lowing only as the need is felt for it. At any stage in the 
history of the conception, men knew what it meant in the 
first sense, for it was used in statements which conveyed 
significant information. But at any particular stage he would 
be a bold man who claimed that he knew what continuity 
meant in the second sense. To take another instance, the 
Newtonian conception of fluxions, defined in terms of in- 
finitesimal quantities, was of obvious practical use and signi- 
ficance, though the conception was riddled with ridicule by 
Berkeley. It turned out later that, though the conception 
had meaning in the first sense, even when it involved in- 
finitesimals, yet its meaning in the second sense was only 
known adequately after more fundamental analysis had ex- 
pressed it in terms of limits. 

The analysis employed by critical philosophy is not 
directed to undermining common-sense, but to refining it. 
Moore goes further, of course, and contends that we abandon 
common-sense only at the risk of finding ourselves unable to 
make significant statements at all. That is perhaps why he 
took, as the motto of his first book, Butler's pregnant say- 
ing " Every thing is what it is and not another thing"; for in 
it he expounds the view that Good as a predicate cannot be 
defined in terms of anything else. It is taken for granted 
that we know what we mean (in the sense of understanding 
the words which express them) when we make moral judg- 
ments, and that we understand in precisely the same way 
as when we make judgments of perception. Logically the 
problem of ethics is on a par with the problem of physics. 
" In both cases " Prof. M. R. Cohen points out " we may be 
said to begin with a set of primitive judgments in the first 
case that certain things exist and in the second case that 


they are good or ought to be. ... The greater difficulties 
of a theory of ethics are due to the greater variability of 
man's moral judgments and their dependence on all sorts of 
conventions which differ according to time and place." The 
lively co-operative discussion of these problems now proceed- 
ing among the Oxford group of moral philosophers is being 
conducted in something of the same spirit, though on 
different lines. They take their start in reaction against what 
was left of utilitarianism in Moore's ethical view. Moore 
had left Right as meaning an act the total effects of which 
are at least as good as those of any other act which the 
agent could have performed instead. For him, the business 
of ethics is primarily the determination of what things are 
intrinsically good. This means, however, that judgments 
concerning what is right involve judgments of means to ends 
in a complex world of social beings, instead of being intuitive 
like judgments of good. That is why the Oxford discussions 
began with Prof. Prichard's contention (in the manner of 
Moore) that previous errors of treatment of Right sprang 
from the initial fallacy of supposing that moral philosophy 
is engaged in giving reasons for holding that what we think 
to be obligatory is really so a fallacy exactly parallel to 
that of supposing that theory of knowledge is concerned with 
the question as to whether what we think to be knowledge 
is really so. Just as in knowledge we begin and end with the 
intuition * this is true ', so also in morals we begin with the 
intuitive judgment ' this is right '. The work of philosophical 
analysis in ethics is then directed to finding out the structure 
of what must be the case if propositions expressing judg- 
ments of these kinds are true. 

The more factual temper of this general attitude is evident 
when we contrast it with the utterances of those who do not 
realize the similarity between moral judgments and judg- 
ments of perception. Thus Prof. L. Hogben excludes moral 
(as well as political and aesthetic) phenomena from rational 
treatment, on account of their ' private ' character as con- 
trasted with phenomena which are ' public ' in the sense of 
gaining universal assent. But surely all men do in fact make 


moral judgments, just as they all make judgments of per- 
ception. He himself, for instance, makes moral judgments : 
as when he says that " Our expectation of life has increased 
as we have learned to worry less about the good life and 
more about the good drain/' It is a sentiment with which 
I am in hearty sympathy: but it implies the moral judg- 
ment that increased expectation of life is good. And such 
moral judgments are phenomena as solidly real as any other 
facts in our world. They are part of the " choir of heaven 
and furniture of earth." They can therefore, presumably, be 
viewed critically and systematically. Prof. Hogben can only 
mean, by excluding them from rational treatment, that all 
attempts to render them intelligible have failed. This seems, 
at one and the same time, to be (a) unduly sceptical since 
some moral (and political and aesthetic) order is discernible 
in the world; and (fo) unduly dogmatic, since the compara- 
tive failure of previous attempts at discovering order may 
be due to incomplete, rather than to incorrect, procedure. It 
may be that, though there is an objective order to be dis- 
covered in these realms, it is harder to find. It has been sug- 
gested by many writers that we occupy the same position in 
regard to our moral and aesthetic judgments as children do in 
respect to their judgments of material things. Thus Dr. P. B. 
Ballard, after describing children's difficulties over even the 
simplest observation of spatial properties, goes on to say that 
in dealing with aspects of the physical world we are their 
superiors: we are more or less grown up. But in dealing 
with spiritual things we are still little children. "Our 
blunders are little children's blunders, due to our fumbling 
after a dimly seen reality." 

It may turn out, as here suggested, that our deficiencies in 
these domains will disappear as the human race sheds its 
more infantile characteristics. An essential factor in this 
development is improvement in our understanding of our- 
selves, and of these other sides of our experience our rela- 
tionship to the world of society and to the world of values. 
More alert understanding of these is, indeed, an essential 
pre-condition for control of our destiny. Mr. Julian Huxley 


has suggested that the biological sciences are now in the 
position occupied by the physical sciences at the middle of 
last century, when they were about to start on their trium- 
phant series of applications to man's control over the material 
world. Enough knowledge already exists, he contends, for 
us to achieve our main biological desires of living longer; of 
moulding the bodies, intellects and temperaments of our 
children into the best possible forms; of creating new kinds 
of animals and plants at leisure; of keeping the balance of 
nature adjusted in our favour; and of controlling population 
and improving its quality whilst retaining variety. But be- 
fore such knowledge can be applied we have to be able to 
work clear of ancient loyalties, of powerful prohibitions and 
observances, which bind society in unreasoning conservatism. 
Only rational treatment of psychological, as well as biological, 
fact can help us in this task. We must now turn, therefore, 
to the methodological issues raised by these less mature 

Biological science, occupying an intermediate position 
between the physical and the social sciences, is rapidly tak- 
ing on some of the characteristics of the former. It is achiev- 
ing wider generalizations, and enjoying the added power 
which comes when measurement can be applied. It is often 
asserted, and more often implied, that there can be no 
science without measurement. This is a mistake. There can 
be purely qualitative ordering of facts in any field : and in 
the development of all the sciences qualitative ordering 
naturally comes first. Measurement does not change the 
character of the process; though it is an advance which 
involves, logically, the long step from merely serial to quan- 
titative relations. Moreover the difficulty of taking this step 
correctly is the same in all domains. 

When we turn to the less mature social sciences qualitative 
ordering is still in the ascendant. But that is the only differ- 
ence. Facts are manipulated in these sciences in ways which 
are formally similar to their treatment in the maturer 


sciences. For they have to be arranged in groups which will 
bring out their significance : attention has to be f ocussed on 
certain properties which will allow the construction of con- 
cepts as bunches of properties, and permit the passage to 
still more general concepts by inductions of a higher order. 
Dr. Wrinch-Nicholson has shown in a very interesting way 
that this procedure is exactly describable in terms of that 
general science of classification which we call geometry. 
" Scientific theory is the geometry of facts/' 

The trouble in the social sciences does not come from 
difficulty in such classification, but from our inability to face 
the facts squarely as a preliminary to discovering their more 
fruitful groupings. Our view is obscured by previous, and 
emotionally held, systems of classification. In our age many 
students of the physical sciences, living in a realm of wide 
generalizations, need the bladder-boys of Swift's satiric im- 
agination to bump them back to the world of common things. 
Students of the biological and social sciences are not likely, 
for generations to come, to fall into this error. Their diffi- 
culty is the opposite one of failing to work themselves clear 
of whole bodies of traditional beliefs, customs and habits. 
Man's first passion is for order. He desires security in society, 
and certainty about the world. This means that facts which 
fall outside a given system have not only no significance for 
the primitive mind : they are not observed at all. 

This was the position, of course, in all sciences during their 
early stages. But it is necessary to stress it here, because it 
probably forms the real ground for the popular prejudice 
against treating social phenomena 'scientifically'. The very 
objectivity, the 'ethical neutrality' of a scientific method- 
ology renders it inapplicable (it is supposed) to any but an 
'ethically neutral' subject-matter: as if it were really true 
that " Who drives fat oxen must himself be fat ". It must be 
obvious that ethical neutrality of method does not necessarily 
mean that the subject-matter need be. 

Apart from these considerations, the problems raised by 
the social sciences are similar in form to those raised by 
physical science. Only, in these less developed domains some 


of the dangers we have already mentioned become more 
serious. We will deal with two of these in detail. 

In discovering the order embodied in a collection of facts 
we must not, in any science, force that order beyond what 
the facts themselves warrant. We have spoken of science as 
the reducing of a complex of facts to intelligible order : yet 
we must always be prepared to find that some facts remain 
stubbornly irreducible to any ' order ' we are likely to discern. 
Indeed the factual discrepancies in a theory are the rough 
edges of the building, showing where the next advance is 
likely to be. It is myth (and not scientific generalization, with 
its successive approximations to truth) which panders to man's 
thirst for finality. " It is the chief glory of science " Prof. 
Hogben rightly remarks "that its answers are always in- 

Though all this is obvious, it is not often recognized as 
fatal to any really tough-minded determinism in these fields. 
A ' methodological determinism ' is still, of course, defensible 
since it encourages us to look for order everywhere. Even 
in the very citadel of apparent disorder, statistical law may 
be achieved: laws which include (as Mr. J. D. Bernal has 
pointed, out) what is in effect the chance interactions of com- 
plexes of a lower order. "The death-rate of a town, for in- 
stance, can be shown to be a function of the amount of money 
it spends on sanitary measures; but the individual deaths 
appear, from the point of view of the town, to be due to 
chance circumstances, though for each individual concerned 
they are determined." Nevertheless, if we wish to adopt a 
properly scientific attitude we must firmly decline to go 
beyond accepting * order ' where we can find it, and must be 
prepared to take 'disorder' at its face value too without 
venturing to say whether it is ultimately disorder or not. 
When Freud finds that he can explain the facts relating to 
the slips and errors of everyday life by means of ordering 
conceptions such as 'dissociation' and 'conflict', we may 
accept his actual findings without being bullied into going 
further and asserting a universal psychological determinism. 

But this is not all. For when we begin to apply such know- 


ledge as is provided by ' order ' of this type, we come upon 
the curious conclusion that the more we know about our 
activities the better are we able to control them. When we 
learn, for instance, that our outbursts of angry annoyance 
over trivialities can usually be traced to a more solid under- 
lying cause, it makes such incidents not only more interesting, 
but also less likely to happen. In short, the more we know of 
the conditions which determine our own behaviour, the freer 
we are. For once we have dragged the factors influencing it 
into the daylight of understanding, we are less at their mercy. 
Those who believe in freewill as a dogma are always uneasily 
disturbed by the working assumption of every science that 
all events form a causal series. They do not realize that with- 
out knowledge of such a series there is no intentional activity : 
that the more we know of the causal series, the greater the 
control. I do not pretend to understand this paradox, I 
merely commend it to your notice. Life can be regarded as 
an observed developing order (not apparently inconsistent 
with freedom) in contrast with that continuous drift back to 
disorder in the material world which is indicated by the 
greatest of our statistical generalizations, the second law of 
thermodynamics. If this is determinism, it is determinism of 
a non-finalist type. 

In precisely the same way we are led (as another conse- 
quence of the rule not to pass beyond what order the facts 
themselves warrant) to limit sharply our working assumption 
of mechanism. For each science is an autonomous study in 
the sense that the worker in each field can alone determine 
the effective form of the concepts he requires for ordering his 
particular domain of experience. He can therefore legiti- 
mately set his face against any attempt to force upon his 
study categories foreign to it. It is true that the methods of 
the various sciences are similar in structure : and that there- 
fore the less mature sciences will continue to find reference 
back to the more mature a fruitful methodological prin- 
ciple. But to go beyond this is to go further than the realities 
of the case warrant. 

Let us consider, for instance, the relation between 


psychology and physiology. There is, in my opinion, a good 
deal of loose thinking about their relationship : and it might 
be worth while to try to differentiate between these two 
studies. The human creature is being perpetually stirred to 
activity either by influences coming from outside, as when I 
blink at a threatening gesture, or make the ' response ' of 
hunger to certain bodily changes (my body being regarded, 
in this connection, as 'outside myself); or by influences 
which seem to come from within, as when I suddenly re- 
member a forgotten engagement and dash for my hat. In 
observing myself I can easily make this distinction between 
response to a stimulus, and activity initiated from within. 
But in observing other people, and still more in observing 
animals, it is difficult to be sure about it. The behaviourist of 
course denies the right of the observer to make use of his own 
consciousness a view difficult to accept, since if he is not 
conscious he can observe nothing at all. We may, then, adopt 
either of two complementary ways of looking at a living 
creature's activities from outside. We may either regard 
them as more or less complicated variations on the simple 
response-to-stimulus theme; and these may be purposive, 
since they are often adapted to achieve an end, as when my 
blinking protects the eye from danger. Or we may regard 
them as the expressions of strivings: purposive also, but 
directed towards, as well as adapted to, the ends of the 
activity. Of these two ways of dealing with the organism's 
activity, the first comes more naturally to the physiologist; 
the second, to the psychologist. The physiologist therefore 
seeks interpretations of the living creature's activity in terms 
of physico-chemical mechanisms involved in its responses : 
the psychologist, on the other hand, looks for interpretations 
of the same facts in terms of what he knows of living activity 
from his own consciousness of it. In this lies the distinction 
between these two cognate and overlapping sciences. 

Now I do not believe that we are scientifically justified 
in assuming either (i) that all the acts of living organisms 
are of the striving kind a view like that of McDougall; 
or (2) that all behaviour is reducible to the ' response-to- 


stimulus program/ I hasten to say that I believe that 
behaviourists are performing a very useful work in show- 
ing us what an unexpectedly long way we can go in study- 
ing behaviour, without using terms drawn from conscious 
experience. But my own feeling on the whole question is 
that we must take up the same attitude here as we did to 
the problem of determinism. The psychologist, as a man 
of science, seeks to interpret the activity of living creatures 
in terms of striving. When he can do so, well and good. 
But sometimes he cannot. There may be acts, correspond- 
ing to what we have previously called disorderly facts, 
which cannot be ordered in these terms. And there may be 
others which are more simply rendered intelligible in terms 
of the ordering conceptions of physiology. We must greet 
behaviouristic successes with a cheer. This seems to me to be 
the only strictly scientific attitude. Moreover, it embodies 
the methodological principle that we should never postulate 
a higher level of behaviour than what is strictly required to 
account for the observed facts. Here is, I suggest, Occam's 
razor of social science. If this is mechanism, it is the mechan- 
ism of a peculiarly Pickwickian kind. 

The hypostasization of ordering conceptions is the mark of 
a younger science; but it has more serious effects in the social 
than in other sciences. One of the oddest things in the history 
of thought is the astonishing way in which men have always 
mixed up what they actually observe with what they (often 
precariously) infer from their observations. I suppose that if 
they did not do this the barrister's work of cross-examination 
would be impossible consisting as it does in persuading a 
witness to add to his evidence of facts the barrister's own 
inferences from them. In scientific work it is this kind of 
confusion which makes it easy to think of ' facts ' and ' order- 
ing conceptions ' as of the same type. It leads us to hyposta- 
size our concepts. So far as the physical sciences go hypostasi- 
zation of ordering conceptions has ceased except as a pre- 
liminary process, until a more generalized type of explanation 
becomes possible. 

In the younger sciences, as we should expect, it is not yet 


recognized that the ordering conceptions are only one step 
towards generalized descriptions of phenomena which shall 
contain only observable factors. Active principles forces, 
chemical affinity and the like have disappeared from 
physical science: but they flourish in the social sciences. 
Thus conceptions such as Instincts or the Unconscious are 
not regarded as merely bringing observed facts of behaviour 
into orderly connection with one another, but as active and 
existent entities 'causing' the creature to behave as it does. 
They are looked upon as inner driving forces urging the 
organism to achieve the ends of its being. In the same way 
Evolution is often regarded as a sort of force, instead of as 
the merely descriptive conception which it is. If there is an 
active unity behind evolution, it is something inferred, but 
not observed. Prof. Ginsberg has analysed what is essentially 
required in the concept of Evolution, and has shown that all 
the methodological requirements are met if we say that Evo- 
lution asserts that there are immanent factors involved in the 
observed processes of change. That is to say, when it is 
possible to describe a body of fact in evolutionary terms we 
may infer that immanent causality is involved. Notice that 
this is formally similar to my suggestion that if a group of 
facts can only be adequately described in psychological terms 
it implies that conscious striving is involved in the observed 
processes. Prof. Ginsberg puts forward this way of regarding 
Evolution as a more desirable method than the earlier usage 
which implies the persistence of an identical subject or un- 
changing substance. The same tendency is even observable 
in theology, the systematic study of man's religious experi- 
ences. For it shows a progressive movement from cruder 
anthropomorphic conceptions of Deity towards more objec- 
tive ones to forms, indeed, transcending personal theism 

The trouble about these ' active principles ', when they are 
not regarded as mere descriptive devices, is that they are 
ready to hand when passion needs them to wave like 
banners in the face of every contradictory fact. Myths, after 
all, are only hypostasized ordering conceptions which have 


outlasted their time. Yet most of our unreasoning loyalties, in 
social affairs as in science, are nothing but the worship of 
unreal, and often personalized, entities of this type. These 
make it easy for us to read more unity into the world than 
there actually is. We are thus led to rely upon divine or evo- 
lutionary purpose instead of upon our own efforts. There is 
created, in this way, a feeling that the incidental poverty and 
dirt and disease in the world must be part of a pre-f ormulated 
plan : these become, indeed, somehow sanctified by resigned 
acceptance of them. Rational thought, which regards poverty 
and disease and dirt as preventable, is therefore felt to be 
something divorced from the life of the spirit. The old atti- 
tude of resignation must be replaced by one which encourages 
man to make the fullest use of his intelligence for the im- 
provement of his lot. The problem of evil, when this has been 
achieved, will be (in Vernon Lee's phrase) the problem, not 
of its toleration by God, but of its diminution by Man. It is 
an attitude, however, which (whilst depending upon a unified 
view of man as a whole) nevertheless refuses resolutely to 
accept the easy comfort of unjustified unities in the world. 
We must therefore enquire what light philosophical studies 
throw upon this latter question. 

We have seen that the main current in philosophy is flow- 
ing in the direction of analysis. The extreme position is 
represented in Bertrand Russell's statement that the most 
fundamental of his beliefs is that "the universe is all spots 
and jumps, without unity, without continuity, without co- 
herence or orderliness, or any of the other properties that 
governesses love." This view is ultimately based on an atti- 
tude to causality which is as old as Hume's, in which causa- 
tion is identified with regular sequence. Hence, though 
Russell regards science as confined to dealing with the causal 
properties of things (though these do not exhaust the rich 
concrete variety of the world), yet this does not involve, on 
his view, any sort of rational system among the world of 
events in time. For strictly speaking one cannot infer any 


material fact from another material fact : they merely happen 
together, and create an expectation of their happening to- 
gether in the future. "Of unity, however vague, however 
tenuous " he says again " I see no evidence in modern science 
considered as a metaphysic. But modern science considered 
as common sense remains triumphant, indeed more trium- 
phant than ever before/' 

I fancy that most people will find Russell's psychologism as 
unsatisfactory as Eddington's subjectivism. They will feel 
that ' expectations * so solidly grounded in experience must be 
more than mere conditioning of men's minds, and have some 
objective reference to an order in the world. So we are led 
back full circle to those older schools of philosophy which 
held that the possibility of rational treatment implied a 
rational world. In these it is often assumed, as in Spinoza's 
system, that the connection between cause and effect is 
identical with or closely allied to that between ground and 
consequent: and that everything in the world we know, is 
therefore, directly or indirectly, causally related to every- 
thing else. The world is a logically intelligible system; and 
the nature of any one thing taken by itself is incomplete and 
internally incoherent apart from the system on which it 
depends. This kind of view provides us with our other ex- 
treme. Our choice is between reality as a rationally intelligible 
system, and reality as a mere aggregate of brute facts. Prob- 
ably the truth is somewhere between these two. It may be, 
as Dr. A. C. Ewing has recently suggested, that philosophical 
analysis of causality has not gone far enough. He shows that, 
as used by common sense and science, we assume that there 
is something more in causality than regular sequence. Just 
as in perception we can analyse our sense-data, and yet feel 
uncertain as to how these are related in the structure to which 
a true judgment of perception refers; so also in judgments 
concerning caused events we can analyse out regular sequence 
as one factor, and yet not know how exactly it is related to 
other (as yet unanalysed) factors in the structure to which a 
true judgment of caused events refers. Causality is for Ewing 
" the application to events of the principle of system, which 


is a cardinal assumption of thought, whether this principle be 
conceived as a pragmatic postulate verified by success, or as a 
necessity of logic, or as a perhaps somewhat dim and con- 
fused but nevertheless genuine intuition of the nature of the 
real world/' Such a ' principle of system ' we shall doubtless 
continue to use, even if we feel too unsure of its meaning (in 
Moore's second sense of that term) to feel that we can assert 
with certainty what kind and degree of systematic unity the 
world really possesses. 

Another way of putting the analytical position is to deny 
the possibility of a purely deductive metaphysic. The diffi- 
culty for those who believe in deduction as the method of 
arriving at knowledge is that they are compelled to find their 
premisses somewhere. They may take them from a body of 
sacred writings; or they may discover them in indubitable 
fact, like Descartes. In either case they are likely to be in- 
volved in " the finding of bad reasons for what we believe 
upon instinct " in explaining concrete facts away, instead of 
just explaining them. This is how Prof. L. S. Stebbing has 
expressed the position. She admits that rejection of a purely 
deductive metaphysic involves discarding a conception of 
philosophical method which has yielded results of great sig- 
nificance for human thought; and adds that, in the hands of 
a philosopher who did not set out to find reasons for common- 
sense beliefs, but merely to expound a vision, such systems 
may have their proper function and possess the beauty of 
works of art. "Hence their spiritual significance. They 
heighten the joy of living." She concludes, however, that 
they do not give knowledge : metaphysics does not consist in 
creation but investigation. This amounts to the same thing 
as the remark of R. Carnap, a Continental representative of 
the analytical school, that "metaphysicians are musicians 
without musical capacity" a sentiment in perfect accord 
with Wittgenstein's " Whereof one cannot speak, thereof one 
must be silent ". 

This analogy between philosophical systems and works of 
art enables us to understand the perennial appeal of the great 
constructive systems of the past. For they are attempts to 


make man see, grasp, comprehend the bodies of knowledge 
he has won : see them, not separately as the various sciences 
see them, but together a true synopsis. That is why William 
James could speak of philosophies as "just so many visions, 
modes of feeling the whole push and seeing the whole drift 
of life "; and why we can speak of such constructions as archi- 
tectonic conceptions which illumine not only the thought of 
our time, but may even strike a light for future ages. In so far 
as they do this, they are a sort of prophetic science. The 
history of philosophy is therefore very largely concerned with 
the herculean labours of great minds to do something which 
can only be achieved by the advance of the sciences. It is not 
therefore useless. To know what the acutest minds of each 
generation have considered to be the structure of the facts 
then known about the world will give us historical perspec- 
tive, by retailing the tortuous tale of human error, and by 
putting up warning barriers at ways which have turned out 
to be dead ends. The latter may be useful to physicists when 
they discover, late in the day, that mind has a part to play in 
knowing, and so tend to exaggerate it. 

The philosopher will always be called on to make efforts at 
synthesis because the generality of his studies marks him out 
as the obvious person to attempt the impossible. That is what 
the philosopher is for. And I see no reason why he should 
not do so, provided that he remembers (as I remarked at the 
beginning) that in going ' beyond science ' he is exercising 
his prophetic rather than his purely philosophical powers. 

This is where studies of man 'in the round' come to our 
aid. For we are carrying into a new era sets of emotionally 
tinged presuppositions which have served us in the past, but 
may now, in altered conditions, bring ruin upon us. Such 
hindrances prevent us, in every department of social affairs, 
from organizing our civilization so as best to serve the ends 
of human well-being. Clearer vision of our mental deficiencies 
is needed if we are to apply our knowledge to a world where 
the blunders of our ancestors have come down to us in our 
blood and in our institutions. Increased critical acumen is an 
ally in this struggle. 


But knowledge, and the control it brings, only marks the 
beginning of our main problems. We have to learn to use 
wisely and well the new instruments placed in our hands. 
This is what calls for construction. Man has risen above the 
unreflective animal level not only by attempting to under- 
stand his experiences but also by evaluating them. Culture, as 
Whitehead has said, is " activity of thought, and receptive- 
ness to beauty, and humane feeling." Just as there are human 
beings more than normally endowed with understanding, so 
there are those that are stung more keenly by beauty, and 
others that surpass the common run in sympathetic insight. 
It is to these gifted souls that we look for guidance, so that 
we may take the order they reveal to us intellectual, 
aesthetic, moral and weave them into the texture of the 
work-a-day world. We have to catch something of the vision 
of sage and artist and saint; and we have to embody their 
visions in the social order. 

Can the constructive hints of ' synoptic science ' help us in 
this task, even though analytical philosophy should withhold 
from us (in its scrupulous regard for intellectual honesty) any 
certainty about ultimate structural unity in the universe? I 
think it possible. A more generous view of man and his world 
would assist us in applying our knowledge wisely by ridding 
us of some of our fears, and by bringing into the daylight of 
understanding the factors involved. The old attitude of 
timorous resignation might thus be replaced by one of hope- 
ful fearlessness a new frame of mind which may well prove 
to be, for a brighter era, what belief in Providence has been 
for the old : a remedy for despair, a vitalizing conception to 
keep man marching breast forward to the future through 
every danger and disappointment. The all-in character of 
philosophical studies gives them a constructive part to play 
in such social engineering. They should prove serviceable, 
even if sometimes disconcerting, collaborators in drafting the 
blue-prints of a new order. 


ABSTRACTION, process of, 373 
Activity, 129 
Acton, 157 
Alexander, S., 370 
Algebra, origin of, 304 
Aliotta, A., 319 
Anatomy, 107 
Andersen, H., 125 
Animal cells, 105 
Anthropology, 154 
scope of, 83 f. 

Anthropomorphism, 195, 363 
Aristotle, 73, 84 
Artist, the, 145 
Astronomical theories, nature of, 


Atomic model, 226 
Averroes, 61 
Avicenna, 60 


Bacon, F., 210, 214 
Bain, 73, 82 
Ballard, P. B., 381 
Barbarism, 96 
Bel, Le, 202 
Berkeley, 132 
Bernal, ]. D., 384 
Bernard, C., 63 
Berzelius, 201 
Binet, 44 

Biochemistry, 116, 208 
Biology, 382 
Birkhoft, G. D., 293 
Blood, 1 08 

circulation of, 108 
Blood-groups, 42 

Body, physiological control of, in 
Bohr's theory, 207 
Boltzmann, L., 353 
Boole, G., 216, 297 
Boole, M. ., 217 
Bosanquet, 323 
Boyle, 133 
Bradley, $. H., 321 


Broad, C. D., 371 
Broghe, de, 228, 231 
Brouwer, 301 
Bruno, G., 84 
Buckle, G. E., 161 
Bukharin, N., 158 
Burt, C., 44 
Bury, ]. B., 158 

Cabot, C., 70 

Campbell, N., 371 

Cantor , G., 294, 324 

Capitalism and religion, 170 

Carey, 160 

Carnap, R., 391 

Carr, W., 131 

Carver, 161 

Causality, 133, 192, 337, 345 

nature of, 346 
Cause, 1 86 

Central Australians, 93 
Chemical technique, 200 
Chemistry, object of, 209 
Chromosomes, 29 f. 
Civilization, dawn of, 96 
Civilized morality, 91 
Classical theory, 353 
Cockcroft, ]. D., 227 
Comte, A., 153 
Consanguineous marriage, 39 
Conservation of energy, 215 
Cosmic radiation, 236 
Creative activity of the spirit, 319 
Croce, B., 157, 326 
Croivther, ]. G., 35 
Culture, 393 

Darwin, C., 28, 78, 92, 229, 231, 

234, 235 
Davenport, 48 
Dawson, Ch., 151 
Dedekind, 324 
Descartes, 185 
Determination and quantum 

physics, 357 


Determinism, 384 

and free will, 366 
Determinists, 353 
Development of religion, 96 
Diagnosis, 68 
Dialectic, 324 
Dick, T., 285 

Dirac, P. A. M., 228, 230, 295 
Direct experimentation on man, 


Domestic group, 92 
Dublin, L. /., 74 
?im, E., 1 6 



Earth's surface history, 239 
Einstein, A., 131 
Ellwood, 1 68 
Emergence, 137, 375 
Environment, 31, 33 
Eternal, the, 148 
Eugenics, 79, 8 1 
Eugenist school, 55 
Eve, A. S., 213 
Evolution, moral value of, 88 
Experiment, 338 
Experimental medicine, 63 

Family, the, 163 
Faraday, M., 214 
Fleming, A., 198 
Fletcher, W. M., 65 
Food, 67 
Force, 287 
Forster, E. M., 373 
Francis, St., 125 
Freedom of the will, 365 
Freudian school, 47 

Galactic system, 272 

Galen, 59 

Galileo, 133, 225, 365 

Gentile, 324 

Geological revolutions, 240 

Gilbert, W., 224 

Gillen, 93 

Ginsberg, M., 388 

Gioberti, V., 321 

Greek mathematics and physics, 

Goblot, 334 

God, 181, 187, 195, 324 

existence of, 188 
Goldenitiieser, 156 


Haldane, ]. B. S., 35, 51 

H alley, E., 293 

Hamilton, W., 231 

Harmony, growth of sense of, 124 

Harvey, W., 62 

Heath, A. E., 369 

Hegel, G. W. F., 319 

Hegelian dialectic, 320 

Hegelianism, 165 

Heisenberg, W., 228, 356 

Hereditary diseases, 38 

Heredity in disease, 37 

Heroic Age, 95 

Herschel, W., 291 

Hilbert, D., 316 

Hippocrates, 58 

History, 156 

Hobhouse, L. T., 87, 166 

H off ding, 137 

Hoff, van't, 202 

Hogben, L., 25, 380, 384 

Holism, 209 

Homer, 125 

Hopkins, F. G., 65 

Human society, 26 

Hume, D., 133 

Huxley, ]., 381 


Ideal mind, 364 
Indeterminists, 349 
Inge, W. R., 45 
Insulin, 68 
Integers, 299 
Intelligence, 45 f. 

and the sexes, 50 

quotient, 47 
Intuitionism, 328, 331 
Ionic theory, 203 
Isostasy, 254 
lyeyasu, 169 


James, W., 392 
, /., 239 


Kant, /., 89, 345 



Kepler, ]., 365 
Kroeber, 156 

Lang, A., 89 

Le Roy, 332 

League of Nations, 67 

Leathes, ]. B., 103 

Leibniz, W. G., 131 

Lemaitre, 286 

Leplay, F., 161 

Levels of scientific knowledge, 311 

Levy, H., 32 

Ltvy-Bruhl, M., 97 

Lewis, G. N., 205 

Life, 260 

and human consciousness, 124 

history of a star, 274 
Lindemann, F. -A., 177 
Living cells, materials of, 105 

organisms, characteristics of, 

1 06 
Locke, ]., 131 

Log ic 3*9 

and history, 337 

and life, 320 

intuitionist, 301 

nature of, 298 
Logistic, 335 
Lowie, 156 
Luther, M., 185 


Macdougall, W., 119 
Mach, E., 178, 328 
Mackenzie, L., 57 
Marrett, R. R., 83 
Marx, K., 161 
Marxism, 161, 164, 178 
Masson, /., 199 
Materialism, 375 
Mathematics, 334 

revival of, 297 

value of, 317 
Maxwell, C., 373 
McTaggart, 218, 321, 370 
Meaning of evil, 198 

of scientific progress, 291 
Measurement, 359 
Mechanism, 385 
Medical doctor, duties of, 76 

Research Council, 64 

Medicine, and society, 82 

history of, 57 
Mendel, G., 28 
Mendel's laws, 29 f. 
Mental disease, 55 

disorder, 51 
Metaphysics, 192, 211 
Meyer, E., 157 
Mill, /., 137 
Mind and body, 120, 129 
Moore, G. E., 378 
Morgan, C. L., 127 
Mott, N. F., 232, 234 
Mountains, origin of, 252 
Mystic, 97 
Mysticism, 179 


Natural selection, 36 
Neanderthal man, 88 
New particles, 225 
Newton, L, 131, 215, 225, 239, 354, 


Osier, W., 57 

Ostwald, W., 161 

Otto, 180 

Out-patient departments, 70 

Paracelsus, 62 

Pareto, 165 

Pasteur, L., 202 

Patriarchalism, 94 

Pauli, W., 228 

Pavlov, 26, 118 

Planck, M., 345 

Plato, 156 

Pierce, B., 297 

Penrose, 51 

Perkin, W. PL, 202 

Philosophy, nature of, 189, 393 

of action, 331 
" Photon," 230 
Physical ideas, 177 
Physiology, origin of, 103 

scope of, 104 
Positivist, 97 
Positron, 237 
Pragmatism, 178, 328 
Prediction, 363 
Preventive medicine, 28 
Prigs, 123 

398 INDEX 

Principle of indeterminacy, 375 
Probability, 367 
Progress, 73, 165 
Psychology, 191 

scope of, 127 
Public health, 71 
Purpose, 149 
Pythagoras, 84, 309 


Quantum theory, 226, 354 
new, 228 

Race and heredity, 43 
Racialist school, 27 
Radioactivity, 205 
Rationality, 319, 344 
Ratzel, 161 
Rayleigh, 217 
Reflexes, 121 
Religion and experience, 179 

and science, 143 
Revelation, 198 
Rhythm, sense of, 124 
Rocks, age of, 255 
Rousseau, J. J., 152 
Russell, B., 337, 389 
Rutherford, 227 

" Rutherford model " of the atom, 


Savage, the, 89 

religion, 98, 100 
Scepticism, 212 
Schrodinger, E., 228, 231 
Science and mathematics, 296 

and modern world, v f. 

and philosophy, 369 

nature of, 185, 340, 368 
Simmel, 166 
Social behaviour, 44 

sciences, 383 

services, 70 

and the art of healing, 70 
Sociology, 151 

Solar system, origin of, 270 
Space, 281 
Spearman, C., 44 
Spencer, B., 93, 97 
Spencer, H., 161 

, Spinoza, 193 
Star, internal structure of, 278 

mass of, 280 
Steggerda, 48 
Sterilisation, 40 

of feeble-minded individuals, 


Strata, origin of, 249 
Sullivan, J. W. N., 372 
Synoptic science, 370, 393 
Synthesis, 392 


Tabu, 96 

Tawney, R. H., 50 

Teleology, 139 

Tennant, 219, 223 

Terman, 44 

Theology, nature of, 190 

Thomson, A., vi 

appreciation of, iii 
Thomson, J. J., 205 
Transfinite numbers, 307 
Trevelyan, 157 
Truth, 338 

and a priori reasoning, 343 
Tylor, E., 96 


Uncertainty principle, 230 
relation, 356 

Valency-linkage, 208 
Verification, 339 
Vesalius, 62 
Viruses, 69 
Vitamins, 66 


Wallace, A. R., 91 
Walton, E. T. S., 227 
Ward, L., 1 66 
Wavicles, 223 
Weber, M., ^169 
White dwarfs, 274 
Whitehead, A. N., 131, 182 
Wiese, von, 166 
Winiarsky, 161 
Wissler, 156 
Wittgenstein, L., 391 
World-picture, 352 
Wrinch-Nicholson, D., 372